X. Mack's Mistake
Here is how Mack solved 38 + 21. He got an answer of 509. Can you find his mistake?
38 = 30 + 8 | ||
21 = 20 + 1 | ||
50 + 9 | = 509 |
- What did Mack do wrong?
- What is the correct answer to Mack's problem?
Here is how Mack solved 38 + 21. He got an answer of 509. Can you find his mistake?
38 = 30 + 8 | ||
21 = 20 + 1 | ||
50 + 9 | = 509 |