adding a two-digit number & a multiple of 10 1.NBT.4

Add within 100, including adding a two-digit number and a one-digit number, and adding a two-digit number and a multiple of 10, using concrete models or drawings and strategies

based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written

method and explain the reasoning used. Understand that in adding two-digit numbers, one adds tens and tens, ones and ones; and sometimes it is necessary to compose a ten.

1.NBT.4 Standard

Let’s count by tens starting with 3…..

3

13

3 + 10 = 13

3

13

23

33

3 + 10 + 10 + 10 = 33

+

10

20

30

33 + 10

= 43

Let’s count by tens starting with 24…..

24

+ =

10

34

34

+ =

10

44

44

+ =

10

54

54

+ =

10

64

What is the pattern?

Now Try These

10 + 4 = 14

Now Try These

20 + 4 = 24

Now Try These

30 + 4 = 34

Now Try These

40 + 4 = 44