1. Subtracting Friendly Numbers by Grade 4

2. are numbers that have 9’s in the Ones like 39 or 59 Tens like 199 or 399 Hundreds like 3999 or 6999

3. We can change numbers into so that they are easier to subtract in our heads! Follow this simple rule: You can change numbers if they: Are close to a ten, hundred or thousand

4. 305 297 305 -6 =299 (a friendly number) 297 -6 = to become 291 Now subtract 299 291 8 - -

5. 202 144 202 -3 =199 (a friendly number) 144 -3 becomes 141 Now subtract 199 141 58

6. 509 386 509 -10 = 499 (a friendly number) 386 -10 becomes 376 Now subtract 499 376 1 23 - -

9. 482 295 + 5 = 487 + 5 = 300 Now subtract 487 300 187 - -

10. 841 303 - 3 = 838 - 3 = 300 Now subtract! 838 300 38 - - 5

11. 831 508 Subtract 8 = 823 Subtract 8 = 500 Now subtract! 823 500 3 23 - -

12. 2 01 2000 Minus 1 to become 1999 Minus 1 to become 200 Now subtract! 1999 200 1 7 99 - -

13. 805 598 Add 2 to become 807 Add 2 to become 600 Now subtract! 807 600 20 7 - -

14. 4000 Subtract 1to become 3999 Subtract 1 to become 2494 Now subtract! 2495 3999 2494 5051 - -

15. The End – now do your own in your scribbler on the next slide! Check them when you’re done all of them.

16. Now do these on your own paper: 1. 800 - 599 2. 3000 - 213 3. 4876- 2999 4. 5226 - 3796 (799 - 598=201) (2999 - 212=2787) (4877 - 3000 =1877) (5230 - 3800=1470) Did you find the mistake?