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Adding Friendly Numbers
Grade 4
are numbers that have 0’s in the
Tens like 30 or 50
Hundreds like 100 or 300
Thousands like 3000 or 6000
We can change numbers into
so that they are easier to add in our heads!
Follow this simple rule:
You can change numbers if they:
Are close to a ten, hundred or thousand
198343
198 +2 =200 (a friendly number)
Subtract 2 to become 341
Now add it all up
200341541
205549
205 -5 =200 (a friendly number)Add 5 to 549 to become 554
Now add it all up
200554754
508383
508 -8 to become 500 (a friendly number)
Add 8 to become 391
Now add it all up
500391891
876313
Add 13 to become 889
Subtract 13 to become 300
Now add it all up
889300
1 1 89
850508
Add 8 to become 858
Subtract 8 to become 500
Now add it all up
858500
1 3 58
89213
Add 11 to become 100
Subtract 11 to become 202
Now add it all up
100202
302
482295 Add 5 to become 300
Now add it all up to make 782
482300782
Now Subtract 5 to become 777 7 77
859508
Add 8 to become 1367
Subtract 8 to become 500
Now add it all up
859500
1 3591 367
4780 Add 5 to become 4785
Subtract 5 to become 2000
Now add it all up
2005
47852000
5876
The End – now do your own on the next slide!
Now do these on your own paper:
1. 850 + 508
2. 89 + 213
3. 876 + 313
4. 226 + 796
(858 + 500=1358)
(100 + 202=302)
(889 + 300 =1189)
(222 + 800=1022)
How did you do?