Work through the levels in order. Type your answer and press Check — open the worked solution if you get stuck. Answers like -6, 3/4 or 0.25 are typed exactly as shown. A ⭐ Bonus Challenge at the end is extra credit — skip it if the rest was hard work.
Level 1 · Warm-up
1 Column add: 376 + 248
Show worked solution
Ones: 6 + 8 = 14, write 4 and trade 1 ten. Tens: 7 + 4 + 1 = 12, write 2 and trade 1 hundred. Hundreds: 3 + 2 + 1 = 6. Answer 624.
2 Column add: 509 + 396
Show worked solution
Ones: 9 + 6 = 15, write 5 and trade 1. Tens: 0 + 9 + 1 = 10, write 0 and trade 1. Hundreds: 5 + 3 + 1 = 9. Answer 905.
3 Column add: 1478 + 265
Show worked solution
Ones: 8 + 5 = 13. Tens: 7 + 6 + 1 = 14. Hundreds: 4 + 2 + 1 = 7. Thousands: 1. Answer 1743.
Level 2 · Core
4 Column add: 2865 + 1476
Show worked solution
Ones: 5 + 6 = 11. Tens: 6 + 7 + 1 = 14. Hundreds: 8 + 4 + 1 = 13. Thousands: 2 + 1 + 1 = 4. Answer 4341.
5 Add all three: 397 + 486 + 215
Show worked solution
397 + 486 = 883, then 883 + 215 = 1098.
6 What must be added to 458 to make 1000?
Show worked solution
458 + 42 = 500, then 500 + 500 = 1000. So 42 + 500 = 542.
Level 3 · Challenge
7 In this column addition, 3▢6 + 245 = 631. What digit belongs in the box?
Show worked solution
631 − 245 = 386, so the first number is 386 and the box holds 8.
8 Two 3-digit numbers add to 1002. One of them is 458. What is the other?
Show worked solution
1002 − 458 = 544. (Check: 458 + 544 = 1002.)
9 A number added to itself gives 1354. What is the number?
Show worked solution
Halve 1354: half of 1300 is 650 and half of 54 is 27, so the number is 677. (677 + 677 = 1354.)
⭐ Bonus Challenge · only if the rest felt easy
10 Column add all three numbers: 386 + 247 + 159
Show worked solution
386 + 247 = 633. Then 633 + 159 = 792. (Ones: 6+7+9 = 22, so write 2 and trade 2 tens.)