The total length of three wooden planks is 8.5 meters. The first plank is 2.75 meters long, and the second plank is 3.5 meters long. What is the length of the third plank?
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ISEE Lower Level Mathematics Achievement Quiz
Practice Decimal Addition Subtraction in ISEE Lower Level Mathematics Achievement with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.
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The total length of three wooden planks is 8.5 meters. The first plank is 2.75 meters long, and the second plank is 3.5 meters long. What is the length of the third plank?
This quiz focuses on Decimal Addition Subtraction, giving you a quick way to practice the rules, question types, and explanations that matter most for ISEE Lower Level Mathematics Achievement.
Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.
The total length of three wooden planks is 8.5 meters. The first plank is 2.75 meters long, and the second plank is 3.5 meters long. What is the length of the third plank?
Explanation: First, add the lengths of the two known planks: 2.75 meters + 3.50 meters = 6.25 meters. Then, subtract this sum from the total length to find the length of the third plank: 8.50 meters - 6.25 meters = 2.25 meters.
A rectangular garden is 12.5 meters long and 7.85 meters wide. A fence is to be built around three sides of the garden, leaving one of the longer sides open. What is the total length of the fence needed?
Explanation: The fence will cover the two shorter sides (widths) and one longer side (length). The total length is the sum of these three sides: 7.85 meters + 7.85 meters + 12.5 meters. First, add the widths: 7.85 + 7.85 = 15.7 meters. Then add the length: 15.7 + 12.5 = 28.2 meters.
After spending 4.75onlunchand2.50 on a snack, Maria had $7.80 left. How much money did Maria have to begin with?
Explanation: To find the starting amount, you must add the money she spent to the money she has left. First, find the total amount spent: 4.75+2.50 = 7.25.Then,addtheamountlefttothetotalspent:7.25 + 7.80=15.05.
David starts with 20.00andbuysabookfor11.45. Emily starts with 15.00andbuysamovieticketfor7.80. What is the difference between the amount of money David has left and the amount Emily has left?
Explanation: First, calculate the money each person has left. David has 20.00−11.45 = 8.55left.Emilyhas15.00 - 7.80=7.20 left. Then, find the difference between their remaining amounts: 8.55−7.20 = $1.35.
A seedling was 5.8 centimeters tall at the beginning of the week. By the end of the week, it was 8.25 centimeters tall. How much did the seedling grow during the week?
Explanation: To find the amount of growth, subtract the initial height from the final height. Remember to align the decimal points by treating 5.8 as 5.80. The calculation is 8.25 cm - 5.80 cm = 2.45 cm.
A baker starts with a 10-kilogram bag of flour. He uses 1.75 kg for bread, 0.9 kg for cookies, and 2.45 kg for cakes. What was the total decrease in the weight of the flour in the bag?
Explanation: The question asks for the total decrease, which is the total amount of flour used. To find this, add the weights of the flour used for each item: 1.75 kg + 0.90 kg + 2.45 kg = 5.10 kg.
The average monthly rainfall for a town is 12.5 centimeters. This month, it rained 3.25 cm the first week, 2.8 cm the second week, and 4.15 cm the third week. How much more rain is needed in the fourth week to meet the monthly average?
Explanation: First, find the total rainfall for the first three weeks: 3.25 cm + 2.80 cm + 4.15 cm = 10.20 cm. Then, subtract this total from the average monthly rainfall to find out how much more is needed: 12.50 cm - 10.20 cm = 2.30 cm.
A tank contains 50.5 liters of water. A pump removes 12.75 liters. Then, an additional 8.5 liters are drained from the tank. How many liters of water are left in the tank?
Explanation: First, find the total amount of water removed by adding the two amounts: 12.75 liters + 8.50 liters = 21.25 liters. Next, subtract the total amount removed from the starting amount of water: 50.50 liters - 21.25 liters = 29.25 liters.
A recipe for trail mix calls for 0.75 kilograms of peanuts, 0.5 kilograms of raisins, and 0.35 kilograms of chocolate chips. If the empty container for the mix weighs 0.12 kilograms, what is the total weight of the container filled with trail mix?
Explanation: First, find the total weight of the trail mix ingredients by adding them together: 0.75 kg + 0.50 kg + 0.35 kg = 1.60 kg. Then, add the weight of the empty container to the weight of the ingredients to find the total weight: 1.60 kg + 0.12 kg = 1.72 kg.
Juan is 1.52 meters tall. His older sister, Sofia, is 1.68 meters tall. His younger brother, Mateo, is 1.35 meters tall. What is the sum of the difference in height between Sofia and Juan, and the difference in height between Juan and Mateo?
Explanation: This problem can be solved in two steps. First, find the difference in height between Sofia and Juan: 1.68 m - 1.52 m = 0.16 m. Second, find the difference in height between Juan and Mateo: 1.52 m - 1.35 m = 0.17 m. Finally, add these two differences together: 0.16 m + 0.17 m = 0.33 m. Alternatively, notice that this sum is equal to the total difference in height between the tallest (Sofia) and the shortest (Mateo): 1.68 m - 1.35 m = 0.33 m.
Jamal has a bottle with 1.75 liters of juice. His friend Chloe has a bottle with 0.95 liters of juice. How much juice should Jamal pour into Chloe's bottle so that they both have the same amount?
Explanation: First, find the total amount of juice: 1.75 liters + 0.95 liters = 2.70 liters. To have the same amount, each would need half of the total, which is 1.35 liters. To find out how much Jamal needs to pour, subtract this target amount from his current amount: 1.75 liters - 1.35 liters = 0.40 liters.
A tailor has a roll of ribbon that is 5 meters long. She cuts off a piece that is 1.25 meters long and another piece that is 0.8 meters long. How much ribbon is left on the roll?
Explanation: First, find the total length of the ribbon that was cut off by adding the two pieces: 1.25 meters + 0.80 meters = 2.05 meters. Then, subtract the total amount cut from the original length of the roll: 5.00 meters - 2.05 meters = 2.95 meters.
The distance from Leo's house to the park is 1.65 kilometers. He walks from his house to the park. On his way back, he takes a longer route that adds 0.4 kilometers to the return trip. What is the total distance Leo walked?
Explanation: The walk to the park is 1.65 km. The return trip is 1.65 km + 0.4 km = 2.05 km. The total distance is the sum of the walk to the park and the return trip: 1.65 km + 2.05 km = 3.70 km.
A container holds 2.5 kilograms of sand. Sam adds 0.85 kg of sand to the container. Then, he scoops out 1.2 kg of sand. What is the final weight of the sand in the container?
Explanation: This is a multi-step problem involving addition and subtraction of decimal numbers. When you see problems with multiple operations happening in sequence, work through them step by step in the order they occur. Start with the initial amount: 2.5 kg of sand. Sam first adds 0.85 kg, so you calculate: 2.5+0.85=3.35 kg. Now Sam scoops out 1.2 kg from this new total: 3.35−1.2=2.15 kg. This gives you the final answer of 2.15 kg. Looking at the wrong answers: Choice A (1.30 kg) represents a common error where you might subtract both the added amount and the scooped amount from the original: 2.5−0.85−1.2=0.45 kg, or possibly make an arithmetic mistake. Choice B (3.35 kg) is the intermediate step—the weight after adding sand but before scooping any out. This traps students who forget to complete the second operation. Choice C (2.85 kg) likely comes from incorrectly adding the scooped amount instead of subtracting it: 2.5+0.85+1.2=4.55 kg, or from other computational errors. The correct answer is D) 2.15 kg. Strategy tip: For multi-step word problems, write down each step as you go. Don't try to do everything in your head at once. Track the running total after each operation to avoid missing steps or making sign errors.
On Monday, Anya jogged 3.8 kilometers and Ben jogged 4.15 kilometers. On Tuesday, Anya jogged 4.3 kilometers and Ben jogged 3.9 kilometers. What is the difference between the total distance Anya jogged and the total distance Ben jogged over the two days?
Explanation: First, find the total distance each person jogged. Anya's total is 3.8 km + 4.3 km = 8.1 km. Ben's total is 4.15 km + 3.90 km = 8.05 km. Then, find the difference between their totals: 8.10 km - 8.05 km = 0.05 km.
A watering can has a capacity of 5.5 liters. It currently contains 1.85 liters of water. How much more water must be added to fill the watering can to exactly 5 liters?
Explanation: The question asks how much water is needed to reach 5 liters, not the full capacity of 5.5 liters. Subtract the current amount of water from the target amount: 5.00 liters - 1.85 liters = 3.15 liters.
A cat weighs 4.55 kilograms. A small dog weighs 6.8 kilograms. A large dog weighs 15.2 kilograms. How much more does the large dog weigh than the cat and the small dog combined?
Explanation: First, find the combined weight of the cat and the small dog: 4.55 kg + 6.80 kg = 11.35 kg. Then, subtract this combined weight from the large dog's weight to find the difference: 15.20 kg - 11.35 kg = 3.85 kg.
The temperature at noon was 15.4 degrees Celsius. By sunset, the temperature had dropped by 6.8 degrees. At midnight, the temperature had dropped another 3.75 degrees from the sunset temperature. What was the temperature at sunset?
Explanation: When you encounter temperature change problems, you need to carefully track what happens at each time point and identify exactly what the question is asking for. Let's work through this step by step. At noon, the temperature was 15.4°C. By sunset, it had dropped 6.8 degrees, so the sunset temperature was 15.4−6.8=8.6°C. The question asks for the temperature at sunset, which is 8.6°C. Notice that the problem gives you additional information about midnight (another 3.75-degree drop), but this is extra information you don't need to answer the question. The midnight temperature would be 8.6−3.75=4.85°C, but that's not what's being asked. Looking at the wrong answers: Choice A (4.85°) is the midnight temperature - this catches students who solve for the wrong time period. Choice B (22.2°) results from adding instead of subtracting the temperature drop (15.4+6.8=22.2), which doesn't make sense since the problem states the temperature "dropped." Choice C (10.55°) appears to come from incorrectly calculating 15.4−6.8+3.75, mixing up the operations or time periods. The key strategy for multi-step word problems is to identify exactly what the question asks for before you start calculating. Underline or circle the specific question, then work systematically through each time point. Don't let extra information confuse you - use only what you need to answer the specific question being asked.
At a market, apples and bananas cost a total of 6.25.Pearsandgrapescostatotalof6.35. Which purchase costs more, and by how much?
Explanation: To compare the costs, subtract the smaller total from the larger total. The cost of pears and grapes (6.35)isgreaterthanthecostofapplesandbananas(6.25). The difference is 6.35−6.25 = 0.10.So,thepearsandgrapescost0.10 more.
Leo bought a notebook for 2.75,apenfor1.49, and an eraser for 0.85.Ifhepaidwitha10 bill, how much change did he receive?
Explanation: First, find the total cost of the items by adding their prices: 2.75+1.49 + 0.85=5.09. Next, subtract the total cost from the amount paid to find the change: 10.00−5.09 = $4.91.