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?