Chapter review

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 · 34 questions

Problems

The complete solutions are available here after each question and on the printable answer-key page.

A1
Add 689 + 435. Show a place-value breakdown.
Show answer and reasoning
Answer: 1124
689 is 600 + 89; add the two parts to 435. The sum is 1,124.
A2
Find 297 + 435 using compensation.
Show answer and reasoning
Answer: 732
Increase 297 by 3 to get a multiple of 100; then subtract that same adjustment from the total. Result: 732.
A3
Calculate 1,765 − 301 by using a nearby hundred.
Show answer and reasoning
Answer: 1464
Rewrite 301 as the nearby multiple of 100 with a small correction. Apply the correction to 1,765 and check the exact answer 1,464.
A4
Leo collected 146 stamps. Mina collected 109 more than Leo. How many does Mina have?
Show answer and reasoning
Answer: 255
Draw Leo’s bar of 146; add the extra segment 109. Mina’s total is 146+109=255.
A5
Add 815 + 487. Show a place-value breakdown.
Show answer and reasoning
Answer: 1302
815 is 800 + 15; add the two parts to 487. The sum is 1,302.
A6
A shop begins with 204 pencils, receives 36, then sells 24. How many pencils remain?
Show answer and reasoning
Answer: 216
First 204+36=240; then take away 24. Result: 216.
A7
Find 99 + 509 using compensation.
Show answer and reasoning
Answer: 608
Increase 99 by 1 to get a multiple of 100; then subtract that same adjustment from the total. Result: 608.
A8
Use equal adjustment to find 485 − 198.
Show answer and reasoning
Answer: 287
Add 2 to BOTH numbers: 487 − 200 = 287. Their difference is unchanged.
A9
A family has 725 reward points. They spend 198 and earn 76. Find the new balance with an efficient method.
Show answer and reasoning
Answer: 603
725−200+2+76=603.
A10
Two classes have 118 students altogether. One class has 14 more. Find each size.
Show answer and reasoning
Answer: 52 and 66
Remove extra 14, divide the remaining 104 by 2 to find 52; larger is 66.
A11
Two collections contain 270 items altogether. One has 64 more than the other. How many are in EACH collection?
Show answer and reasoning
Answer: 103 and 167
Remove the extra 64; 270 − 64 = 206. Two equal parts are 103 each. Larger part is 103 + 64 = 167.
A12
Find 1,386 − 561 by breaking apart the amount subtracted.
Show answer and reasoning
Answer: 825
Decompose 561 into tens and ones, subtract each part from 1,386, and check the difference 825.
A13
A shop begins with 410 pencils, receives 100, then sells 50. How many pencils remain?
Show answer and reasoning
Answer: 460
First 410+100=510; then take away 50. Result: 460.
A14
What must be added to 8 to make 100?
Show answer and reasoning
Answer: 92
The missing part is 100 − 8 = 92; check 8 + 92 = 100.
A15
A school library has 200 books. 120 are on the front shelf. How many are elsewhere?
Show answer and reasoning
Answer: 80
The 200 books are the whole, 120 is a part. Subtract: 200 − 120 = 80.
A16
Calculate 1,639 + 199 by using a nearby hundred.
Show answer and reasoning
Answer: 1838
Rewrite 199 as the nearby multiple of 100 with a small correction. Apply the correction to 1,639 and check the exact answer 1,838.
A17
A school library has 282 books. 154 are on the front shelf. How many are elsewhere?
Show answer and reasoning
Answer: 128
The 282 books are the whole, 154 is a part. Subtract: 282 − 154 = 128.
A18
Find 1,280 − 457 by breaking apart the amount subtracted.
Show answer and reasoning
Answer: 823
Decompose 457 into tens and ones, subtract each part from 1,280, and check the difference 823.
A19
Add 563 + 561. Show a place-value breakdown.
Show answer and reasoning
Answer: 1124
563 is 500 + 63; add the two parts to 561. The sum is 1,124.
A20
A child claims 504−197=301. Use compensation to explain and correct.
Show answer and reasoning
Answer: 307
504−200+3=307; the child failed to return the 3.
A21
Find 1,208 − 509 by breaking apart the amount subtracted.
Show answer and reasoning
Answer: 699
Decompose 509 into tens and ones, subtract each part from 1,208, and check the difference 699.
A22
A shop begins with 147 pencils, receives 23, then sells 67. How many pencils remain?
Show answer and reasoning
Answer: 103
First 147+23=170; then take away 67. Result: 103.
A23
Find 198 + 561 using compensation.
Show answer and reasoning
Answer: 759
Increase 198 by 2 to get a multiple of 100; then subtract that same adjustment from the total. Result: 759.
A24
What must be added to 10 to make 100?
Show answer and reasoning
Answer: 90
The missing part is 100 − 10 = 90; check 10 + 90 = 100.
A25
Two collections contain 230 items altogether. One has 50 more than the other. How many are in EACH collection?
Show answer and reasoning
Answer: 90 and 140
Remove the extra 50; 230 − 50 = 180. Two equal parts are 90 each. Larger part is 90 + 50 = 140.
A26
What must be added to 759 to make 1,000?
Show answer and reasoning
Answer: 241
The missing part is 1,000 − 759 = 241; check 759 + 241 = 1,000.
A27
Two collections contain 60 items altogether. One has 18 more than the other. How many are in EACH collection?
Show answer and reasoning
Answer: 21 and 39
Remove the extra 18; 60 − 18 = 42. Two equal parts are 21 each. Larger part is 21 + 18 = 39.
A28
Calculate 1,513 − 98 by using a nearby hundred.
Show answer and reasoning
Answer: 1415
Rewrite 98 as the nearby multiple of 100 with a small correction. Apply the correction to 1,513 and check the exact answer 1,415.
A29
Explain why (300+57)+43 can be found as 300+(57+43).
Show answer and reasoning
Answer: 400
Grouping the same addends in a different way preserves the total; 57+43=100.
A30
A school library has 241 books. 137 are on the front shelf. How many are elsewhere?
Show answer and reasoning
Answer: 104
The 241 books are the whole, 137 is a part. Subtract: 241 − 137 = 104.
A31
Leo collected 115 stamps. Mina collected 100 more than Leo. How many does Mina have?
Show answer and reasoning
Answer: 215
Draw Leo’s bar of 115; add the extra segment 100. Mina’s total is 115+100=215.
A32
Use equal adjustment to find 631 − 297.
Show answer and reasoning
Answer: 334
Add 3 to BOTH numbers: 634 − 300 = 334. Their difference is unchanged.
A33
Leo collected 177 stamps. Mina collected 118 more than Leo. How many does Mina have?
Show answer and reasoning
Answer: 295
Draw Leo’s bar of 177; add the extra segment 118. Mina’s total is 177+118=295.
A34
Use equal adjustment to find 339 − 99.
Show answer and reasoning
Answer: 240
Add 1 to BOTH numbers: 340 − 100 = 240. Their difference is unchanged.

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