Roots of Reason
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Decimals Without Paper · Grade 5 · 5.NBT.B.7 and 5.NBT.A.2
Decimals in Your Head
Name
Date
Time
Score / 24
Name the place before you answer. No column work, and no rewriting the numbers.
1
Make One Whole
look for the pair that fills the whole
1. 0.7 + 0.3 =
2. 1 - 0.4 =
3. 0.85 + 0.15 =
4. 1 - 0.62 =
5. 0.45 + 0.55 =
6. 1 - 0.08 =
2
Move the Places
each ten moves every digit one place
7. 3.4 × 10 =
8. 0.52 × 100 =
9. 47 ÷ 10 =
10. 6.3 ÷ 10 =
11. 0.8 × 100 =
12. 250 ÷ 100 =
3
Add and Subtract by Place
tenths onto tenths, hundredths onto hundredths
13. 1.2 + 0.35 =
14. 2.7 - 0.5 =
15. 0.46 + 0.3 =
16. 3.05 + 0.4 =
17. 1.6 - 0.25 =
18. 4.5 - 1.2 =
4
Whole Number Fact, Then the Point
do the fact you know, then place the point
19. 0.3 × 4 =
20. 0.6 × 5 =
21. 2.4 ÷ 6 =
22. 0.25 × 4 =
23. 1.5 ÷ 3 =
24. 0.9 ÷ 3 =
Roots of Reason
rootsofreason.org
Decimals Without Paper · Grade 5 · 5.NBT.B.7 and 5.NBT.A.2
Decimals in Your Head
Each band is one mental route. A student missing a whole band needs the route taught, not more items.
1
Make One Whole
the missing part of one, in tenths or hundredths
1. 0.7 + 0.3 = 1
2. 1 - 0.4 = 0.6
3. 0.85 + 0.15 = 1
4. 1 - 0.62 = 0.38
5. 0.45 + 0.55 = 1
6. 1 - 0.08 = 0.92
2
Move the Places
times ten shifts left, divide by ten shifts right
7. 3.4 × 10 = 34
8. 0.52 × 100 = 52
9. 47 ÷ 10 = 4.7
10. 6.3 ÷ 10 = 0.63
11. 0.8 × 100 = 80
12. 250 ÷ 100 = 2.5
3
Add and Subtract by Place
line up the places, never the last digits
13. 1.2 + 0.35 = 1.55
14. 2.7 - 0.5 = 2.2
15. 0.46 + 0.3 = 0.76
16. 3.05 + 0.4 = 3.45
17. 1.6 - 0.25 = 1.35
18. 4.5 - 1.2 = 3.3
4
Whole Number Fact, Then the Point
count the places in the factors, or read the quotient as tenths
19. 0.3 × 4 = 1.2
20. 0.6 × 5 = 3
21. 2.4 ÷ 6 = 0.4
22. 0.25 × 4 = 1
23. 1.5 ÷ 3 = 0.5
24. 0.9 ÷ 3 = 0.3