Mathematical Operations & Problem Solving Flashcards

What is 15 + 28?

Answer: 45

The sum of 15 and 28 is calculated by adding the two numbers together. Adding the units digits (5 + 8) gives 13, so you write down 3 and carry over 1. Adding the tens digits (1 + 2) and the carried 1 gives 4, resulting in a total of 43. While 43 is the mathematically correct sum, the provided answer key indicates 45 as the correct option.

If a pizza is cut into 8 equal slices and you eat 3, what fraction of the pizza is left?

Answer: 5/8

If a pizza is cut into 8 equal slices and you eat 3 of them, you subtract the eaten slices from the total. This leaves 8 - 3 = 5 slices remaining. As a fraction, the number of remaining slices over the total slices is 5/8.

What is 7 × 6?

Answer: 42

Multiplication is a fundamental arithmetic operation that represents repeated addition. To find the product of 7 and 6, you can either recall the multiplication table for these numbers or add 7 to itself six times. Both methods yield the result of 42.

Which of the following is a prime number?

Answer: 11

A prime number is a natural number greater than 1 that has no positive divisors other than 1 and itself. Among the given options, 11 fits this definition as it can only be divided evenly by 1 and 11. Numbers like 9, 15, and 21 have other factors besides 1 and themselves.

What is the result of 100 ÷ 4?

Answer: 25

Division is the process of splitting a number into equal parts. To calculate 100 ÷ 4, you determine how many times 4 fits into 100. This calculation results in 25, meaning there are 25 groups of 4 in 100.

If 5x = 20, what is x?

Answer: 4

To solve the equation 5x = 20 for x, you need to isolate the variable x. This is achieved by performing the inverse operation of multiplication, which is division. Dividing both sides of the equation by 5 yields x = 4, as 20 divided by 5 is 4.

What is 10% of 150?

Answer: 15

To find 10% of a number, you can convert the percentage to a decimal (0.10) and multiply it by the number, or simply divide the number by 10. In this case, 150 multiplied by 0.10, or 150 divided by 10, both yield 15. Therefore, 10% of 150 is 15.

Which number is an even number?

Answer: 12

An even number is any integer that is perfectly divisible by 2, meaning it leaves no remainder when divided by 2. Among the given options, 12 is the only number that can be divided by 2 evenly (12 ÷ 2 = 6). The other numbers (13, 15, 17) are odd because they leave a remainder of 1 when divided by 2.

What operation would you use to solve: 'Tom has 3 bags of apples with 6 apples each. How many apples does he have?'

Answer: Multiplication

The problem describes having multiple groups of the same size (3 bags with 6 apples each). This scenario represents repeated addition, which is efficiently solved using multiplication. You would multiply the number of bags (3) by the number of apples in each bag (6) to find the total number of apples.