3A · Chapter 2 · Practice
Practice A
Attempt independently, then review the full reasoning in the answer key.
Attempt independently, then review the full reasoning in the answer key. No name, account, or answer is transmitted to any server.
Assessment · 18 questions
Problems
The complete solutions are available here after each question and on the printable answer-key page.
- A1
Add 2,003 + 345. Show a place-value breakdown.
Show answer and reasoning
Answer: 2348
2,003 is 2,000 + 3; add the two parts to 345. The sum is 2,348.
- A2
Add 2,129 + 397. Show a place-value breakdown.
Show answer and reasoning
Answer: 2526
2,129 is 2,100 + 29; add the two parts to 397. The sum is 2,526.
- A3
Add 2,255 + 271. Show a place-value breakdown.
Show answer and reasoning
Answer: 2526
2,255 is 2,200 + 55; add the two parts to 271. The sum is 2,526.
- A4
Find 99 + 401 using compensation.
Show answer and reasoning
Answer: 500
Increase 99 by 1 to get a multiple of 100; then subtract that same adjustment from the total. Result: 500.
- A5
Find 198 + 453 using compensation.
Show answer and reasoning
Answer: 651
Increase 198 by 2 to get a multiple of 100; then subtract that same adjustment from the total. Result: 651.
- A6
Find 297 + 505 using compensation.
Show answer and reasoning
Answer: 802
Increase 297 by 3 to get a multiple of 100; then subtract that same adjustment from the total. Result: 802.
- A7
Find 2,678 − 635 by breaking apart the amount subtracted.
Show answer and reasoning
Answer: 2043
Decompose 635 into tens and ones, subtract each part from 2,678, and check the difference 2,043.
- A8
Find 2,678 − 509 by breaking apart the amount subtracted.
Show answer and reasoning
Answer: 2169
Decompose 509 into tens and ones, subtract each part from 2,678, and check the difference 2,169.
- A9
Find 2,856 − 561 by breaking apart the amount subtracted.
Show answer and reasoning
Answer: 2295
Decompose 561 into tens and ones, subtract each part from 2,856, and check the difference 2,295.
- A10
Use equal adjustment to find 509 − 99.
Show answer and reasoning
Answer: 410
Add 1 to BOTH numbers: 510 − 100 = 410. Their difference is unchanged.
- A11
Use equal adjustment to find 655 − 198.
Show answer and reasoning
Answer: 457
Add 2 to BOTH numbers: 657 − 200 = 457. Their difference is unchanged.
- A12
Use equal adjustment to find 451 − 297.
Show answer and reasoning
Answer: 154
Add 3 to BOTH numbers: 454 − 300 = 154. Their difference is unchanged.
- A13
What must be added to 88 to make 100?
Show answer and reasoning
Answer: 12
The missing part is 100 − 88 = 12; check 88 + 12 = 100.
- A14
What must be added to 9 to make 1,000?
Show answer and reasoning
Answer: 991
The missing part is 1,000 − 9 = 991; check 9 + 991 = 1,000.
- A15
What must be added to 70 to make 100?
Show answer and reasoning
Answer: 30
The missing part is 100 − 70 = 30; check 70 + 30 = 100.
- A16
Calculate 2,003 − 98 by using a nearby hundred.
Show answer and reasoning
Answer: 1905
Rewrite 98 as the nearby multiple of 100 with a small correction. Apply the correction to 2,003 and check the exact answer 1,905.
- A17
Calculate 2,129 + 199 by using a nearby hundred.
Show answer and reasoning
Answer: 2328
Rewrite 199 as the nearby multiple of 100 with a small correction. Apply the correction to 2,129 and check the exact answer 2,328.
- A18
Calculate 2,255 − 301 by using a nearby hundred.
Show answer and reasoning
Answer: 1954
Rewrite 301 as the nearby multiple of 100 with a small correction. Apply the correction to 2,255 and check the exact answer 1,954.