Question

6. How could you check the answer to 27-15 12 using addition?A. 27 15 12B. 27 12 15C. 12 15 27D. 15-12 277. Which of the following uses estimation to check 267 -154 113?A. 300 200 100B. 113 154 267C. 270 150 120D. 300 150 1508. Subtract the quotient of 18 and 2 from the sum of 22 and 9.A. 5B. 23C.4D. 22LPFU

Answer 1

27 - 15 = 12
Adding 15 to both sides, we have,
27 - 15 + 15 = 12 + 15
i.e. 27 = 12 + 15
Answer: C [12 + 15 = 27]

To calculate by estimation, round each number to the nearest ten, hundred, ets as the case may be.
Here, rounding to the nearest ten, we have,
267 - 154 = 270 - 150 = 120.
Answer: C

Quotient of 18 and 2 = 18/2 = 9
Sum of 22 and 9 = 22 + 9 = 31
Subtracting the quotient of 18 and 2 from the sum of 22 and 9, we have:
31 - 9 = 22
Answer: D