Show:
Base 10 blocks
Adjust addends to make friendly numbers
Decompose 2 addends
Decompose 1 addend
Make 100
100

15 + 3=

18

100

27 + 38 =

27 + 38=

30 + 35=65 

or

25 + 40= 65

100

24 + 33=

20 + 30= 50

4 +3= 7

50 + 7= 57

100

27 + 35=

27 + 30 + 5=62

100

63 + ? =100

37

200

18 + 5=

23

200

32 + 44=

32 + 44=

30 + 46=76

or

36 + 40=76

200

34 + 14=

30 + 10= 40

4 + 4 = 8

40 + 8= 48

200

33 + 18=

33 + 10 + 8= 51

200

49 + ? =100

51

300

23 + 42 =

65

300

18 + 9=

20 + 7=27 

or 

17 + 10=27

300

61 + 38=

60 + 30= 90

1 + 8= 9

90 + 9=99

300

28 + 44=

28 + 40 + 4=72

300

75 + ?=100

25
400

38 + 14 =

52

400

29 + 53=

30 + 52=82

or

32 + 50=82

400

26 + 19=

20 + 10= 30

6 + 9=15

30 + 15= 45

400

43 + 16=

43 + 7+ 9= 59

400

33 + ? = 100

67

500

44 + 26=

70

500

49 + 21

50 + 20=70

48 + 22= 70

500

36 + 36=

30 + 30=60

6 + 6=12

60 + 12=72

500

45 + 15=

45 + 5 + 10= 60

500

18 + ? = 100

82