All PSAT Math Resources
Example Question #501 : Arithmetic
simplify: 0.2 ÷ 0.04
0.2 ÷ 0.04 <- easiest way to approach is to move the decimal to the right (the same amount of spaces on each side) so that the decimal disappears
since 0.04 has 2 spaces and 0.2 only has 1, move the decimal 2 spaces to the right on each side
0.2 ÷ 0.04 = 20 ÷ 4 = 5
Example Question #41 : Other Decimals
If the cost of 20 equally priced pencils cost $5.80, then at the same rate what is the greatest number of pencils you can purchase for $50?
Remeber for this problem that you cannot spend more than $50. First find the price of each pencil by 5.80/20 = 29 cents. And then use this to do 50/0.29 = 172.41. So the greatest number of pencils you can purchase for $50 is 172 pencils.
Example Question #42 : Other Decimals
Charlie has charges on his credit card of $63.70, $37.32, and $81.78. If he pays down half his bill at once, and then pays the rest in four equal monthly installments, how much is each monthly installment?
Adding all the charges together and dividing by 2 yields $91.40. Dividing this by 4 yields a monthly installment of $22.85.
Example Question #43 : Other Decimals
Multiply both the numerator and denominator by some power of 10 to get rid of the decimals; in this case, multiply both by 10,000.
Example Question #11 : Decimal Operations
Which number has 2.8 as its reciprocal?
The number that has 2.8 as its reciprocal is, in return, the reciprocal of 2.8.
The reciprocal of this can be found by switching the numerator and the denominator. This is .
Example Question #12 : Decimal Operations
23 grams of sodium are equal to atoms. How many atoms comprise one milligram of sodium?
(Select the closest answer)
23 grams are equal to 23,000 milligrams, so to find the number of atoms in one milligram, divide: