Multiply Side Lengths for Area - 3rd Grade Math

Maya's rectangular room is 10 feet long and 9 feet wide. What is its area?
Answer: 90 square feet 90 square feet is correct because $10 \times 9 = 90$ square feet. 38 square feet is incorrect; it doesn't match multiplying the room's dimensions. 90 feet is incorrect because it's missing the correct square-unit label for area. 19 square feet is incorrect; it comes from adding 10 and 9 instead of multiplying.
A rectangular garden bed is $7$ feet long and $5$ feet wide. Jake wants to plant flowers that need $1$ square foot of space each. He already planted $8$ flowers. How many more flowers can he plant in the remaining space?
Answer: $27$ more flowers can be planted First, find the total area of the garden: $7 \times 5 = 35$ square feet. Since Jake already planted $8$ flowers (using $8$ square feet), the remaining space is $35 - 8 = 27$ square feet, so he can plant $27$ more flowers. Choice B gives the total area without subtracting the planted flowers. Choice C incorrectly adds the perimeter ( $7 + 5 = 12$ ) to the area and then subtracts: $35 + 12 - 8 = 43$ . Choice D incorrectly uses the perimeter ( $2 \times 7 + 2 \times 5 = 24$ ) instead of area.
Chen paints a canvas that is 9 inches long and 6 inches wide. What is the perimeter of the canvas?
Answer: 30 inches The perimeter of the canvas is the sum of all four sides: 2 x (9 + 6) = 30 inches, so Choice B is correct. Choice A (15 inches) adds the length and width once but forgets to double the sum. Choice C (18 inches) doubles only the length and ignores the width. Choice D (54 square inches) is the area of the canvas, not the perimeter, and uses the wrong type of unit for this question.
Chen's canvas is 9 inches long and 6 inches wide. What is the area?
Answer: 54 square inches Multiplying the length and width, 9 inches times 6 inches, gives 54 square inches, matching choice B. Choice A adds the length and width instead of multiplying them. Choice C uses the perimeter method instead of area. Choice D comes from multiplying the wrong numbers together.
A rectangle has an area of 24 square inches. Which of the following could be its side lengths?
Answer: 2 inches by 12 inches When you see a question about the area of a rectangle, remember the formula: $\text{Area} = \text{length} \times \text{width}$ Your job is to find which pair of side lengths multiplies to give the target area — in this case, 24 square inches. Check each option by multiplying the two side lengths. For A, $2 \times 12 = 24$ , which matches the area exactly. That's your answer. Option B gives $4 \times 5 = 20$ square inches, which is too small. Option C gives $3 \times 9 = 27$ square inches — close to 24, but not equal, so it doesn't work. Option D gives $6 \times 5 = 30$ square inches, which is too large. Notice how the wrong answers are all "near misses" — they're close to 24 but not exact. This is a common trap: the test wants to see if you'll actually multiply instead of just guessing based on numbers that "look right." A helpful strategy is to know the factor pairs of common numbers. For 24, the whole-number factor pairs are $1 \times 24$ , $2 \times 12$ , $3 \times 8$ , and $4 \times 6$ . If a rectangle has an area of 24 square inches with whole-number sides, its dimensions must be one of these pairs. Memorizing factor pairs of numbers like 12, 18, 24, and 36 will help you answer area questions quickly on future tests.
Use the table to answer the question. Which rectangle has the largest area?
Answer: Rectangle Y Areas: W = 3 × 9 = 27, X = 4 × 6 = 24, Y = 5 × 7 = 35, Z = 8 × 4 = 32. Y has the largest area. A student adding sides might pick W (12) or Z (12) as a tie.
A rectangle is 5 centimeters long and 8 centimeters wide; what is the area?
Answer: 40 square centimeters Area equals length times width, so 5 times 8 gives 40 square centimeters. Choice A comes from adding the length and width instead of multiplying. Choice B is the perimeter of the rectangle, not the area. Choice C comes from a multiplication error.
A poster is 6 inches wide and 8 inches tall. A second poster is 4 inches wide and 9 inches tall. How much greater is the area of the first poster than the second?
Answer: 12 square inches Whenever you see a question comparing the sizes of two rectangles, remember that area measures the space inside a shape and is found by multiplying width × height. The units will be square inches (or square feet, etc.) because you're covering a two-dimensional space. Start by finding each poster's area separately. The first poster is 6 inches wide and 8 inches tall, so its area is $6 \times 8 = 48$ square inches. The second poster is 4 inches wide and 9 inches tall, so its area is $4 \times 9 = 36$ square inches. The question asks how much greater the first area is, which means subtract: $48 - 36 = 12$ square inches. That matches choice C. Choice A (0) would only be correct if the two posters had the same area — but they don't. Choice B (1) is the difference in one of the dimensions (like 9 - 8), not the difference in area; this is a common trap when students compare side lengths instead of areas. Choice D (84) is what you get if you add the two areas together (48 + 36 = 84) instead of subtracting, or if you confuse "how much greater" with "total." A helpful tip: when a word problem asks "how much greater" or "how much more," that's always a subtraction clue — but first make sure you've calculated the right quantity (area, not perimeter or a single side). Underline the key words in the question to keep yourself on track.
A rectangular kitchen tile is 4 inches by 6 inches. Kevin places 3 of these tiles in a row so that their 6-inch sides are touching. What is the area of the bigger rectangle he makes?
Answer: 72 square inches When you see a question about combining shapes, picture what's happening before you calculate. Here, each tile is a 4-by-6 rectangle, and Kevin lines up three tiles so their 6-inch sides touch. That means the 6-inch sides are the ones stacked together, so the new rectangle has one side that stays 6 inches long, and the other side becomes $4 + 4 + 4 = 12$ inches. To find the area of the bigger rectangle, multiply length by width: $6 \times 12 = 72 \text{ square inches}$ That matches choice A. You can also check this by finding the area of one tile and multiplying by 3: each tile is $4 \times 6 = 24$ square inches, and $24 \times 3 = 72$ square inches. Both methods give the same answer, which is a great way to double-check. Choice B (48) comes from only combining two tiles instead of three ( $24 \times 2$ ). Choice C (24) is the area of just one tile — a trap if you forget to combine them. Choice D (96) comes from mistakenly adding the 6-inch sides together ( $6+6+6=18$ ) and multiplying by something like $18 \times \text{a wrong number}$ , or from doubling the correct area. Tip: When tiles are pushed together along a certain side, that side length stays the same in the big shape — only the other side grows. Draw a quick sketch before multiplying; it prevents mix-ups about which side gets longer.
A rectangular parking space is 9 feet wide and 7 feet long. Next to it, a second parking space is a square with sides of 8 feet. Which parking space has the greater area, and by how much?
Answer: The square, by 1 square foot When a question asks you to compare areas of different shapes, remember that area is always measured in square units, and you find it by multiplying the dimensions that cover the shape. For a rectangle, area equals length times width. For a square, since all four sides are equal, area equals side times side. Start by finding each area separately. The rectangular parking space measures 9 feet by 7 feet, so its area is $9 \times 7 = 63$ square feet. The square parking space has sides of 8 feet, so its area is $8 \times 8 = 64$ square feet. Comparing them, the square is larger, and the difference is $64 - 63 = 1$ square foot. That makes B correct. Choice A flips the comparison — it correctly identifies the 1 square foot difference but wrongly says the rectangle is bigger; a common mistake when you rush and assume the shape with the longer single side (9 feet) must have more area. Choice C makes the same "rectangle is bigger" error and also miscalculates the difference. Choice D correctly picks the square but overstates the gap by 1, which can happen if you subtract carelessly. A helpful tip: don't judge area by looking at just one dimension. A shape with a longer side isn't automatically bigger — you have to multiply both dimensions. In fact, for a fixed perimeter, squares often "hold" more area than long, thin rectangles, which is exactly what's happening here.
Chen's canvas is 9 inches long and 6 inches wide. Find the area.
Answer: 54 square inches The area of Chen's canvas is length times width: 9 times 6 equals 54 square inches, so A is correct. Choice B (42) does not match multiplying 9 by 6. Choice C (30) is the perimeter of the canvas, not its area. Choice D (63) results from using the wrong side length in the multiplication.
Refer to the figure. Each small square represents 1 square centimeter. What is the area of the shaded rectangle?
Answer: 45 square centimeters The rectangle is 9 squares by 5 squares. Area = 9 × 5 = 45 square centimeters. Choice A counts only one row. Choice B is the perimeter. Choice C is 9 + 9 = 18.
A rectangular tabletop is 6 feet long and 9 feet wide; what is the area?
Answer: 54 square feet The area is C) 54 square feet, since 6x9=54. Choice A (30) comes from adding the length and width instead of multiplying. Choice B (108) is double the correct product. Choice D (42) results from a multiplication error, such as mistakenly computing 6x7.
Lisa has a rectangular piece of paper that is 5 inches wide and 11 inches long. She cuts off a strip that is 1 inch wide along the entire length. What is the area of the remaining piece of paper?
Answer: 44 square inches The original paper has an area of 5 times 11, which is 55 square inches. Cutting off a 1-inch-wide strip along the 11-inch length removes 1 times 11, or 11 square inches, leaving 55 minus 11, which is 44 square inches, matching choice B. Choice A miscalculates the strip's area. Choice C subtracts too much. Choice D uses the wrong dimension for the strip.
A rectangle has length 5 units and width 8 units. What is the area?
Answer: 40 square units The area of a rectangle is length times width, so 5 times 8 gives 40 square units. Choice A (13 square units) comes from adding 5 and 8 instead of multiplying. Choice C (64 square units) comes from multiplying 8 by itself instead of by 5. Choice D (26 square units) comes from using the perimeter formula instead of the area formula.
Jamal's garden is 6 meters long and 4 meters wide. What is the area of the garden?
Answer: 24 square meters The area of Jamal's garden is 6 x 4 = 24 square meters, so Choice D is correct. Choice A (10 square meters) adds the length and width instead of multiplying them. Choice B (20 square meters) is the perimeter of the garden, 2 x (6 + 4) = 20, not the area. Choice C (18 square meters) comes from a multiplication slip, such as 6 x 3 instead of 6 x 4.
Maria is making a quilt with rectangular patches. She has enough fabric to make patches with a total area of $36$ square inches. If she cuts her first patch to be $4$ inches long and $3$ inches wide, how many more square inches of fabric does she have left for other patches?
Answer: $24$ square inches First, find the area of Maria's first patch by multiplying the side lengths: $4 \times 3 = 12$ square inches. Then subtract this from her total fabric: $36 - 12 = 24$ square inches remaining. Choice B incorrectly adds the perimeter ( $4 + 3 = 7$ ) instead of finding area, then subtracts: $36 - 7 = 29$ . Choice C incorrectly subtracts only one dimension: $36 - 4 = 32$ . Choice D incorrectly subtracts only the other dimension: $36 - 3 = 33$ .
Sarah draws two rectangles. Rectangle A has side lengths of $3$ inches and $8$ inches. Rectangle B has side lengths of $4$ inches and $6$ inches. How much greater is the area of Rectangle A than the area of Rectangle B?
Answer: $0$ square inches Rectangle A has an area of 3 x 8 = 24 square inches, and Rectangle B has an area of 4 x 6 = 24 square inches. Since both areas are equal, Rectangle A is 0 square inches greater than Rectangle B, so Choice D is correct. Choices A, B, and C all assume the two areas are different, but computing each area shows they are exactly the same.
A rectangular patio is 12 feet long and 8 feet wide. What is its area?
Answer: 96 square feet The area of a rectangle equals length times width, so 12 x 8 = 96 square feet is correct. Choice B (40 square feet) comes from finding the perimeter instead, 2 x (12 + 8) = 40. Choice C (20 square feet) results from adding the length and width instead of multiplying, 12 + 8 = 20. Choice D (84 square feet) comes from a multiplication slip, such as multiplying 12 by 7 instead of 8.
A rectangular sandbox is 7 feet long and 5 feet wide. What is the area?
Answer: 35 square feet Multiplying the length and width, 7 feet times 5 feet, gives 35 square feet, matching choice D. Choice A adds the length and width instead of multiplying. Choice B comes from multiplying the wrong numbers together. Choice C uses only part of one dimension in the calculation.

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