Anchor Chart · Grade 5 · 5.NBT.B.7
Adding and Subtracting Decimals
Add tenths to tenths and hundredths to hundredths. Lining up the decimal points keeps every digit in its place.
1Same Place, Same Column
Tens
Ones
Tenths
Hundredths
1
1
2
.
7
5
+
3
.
4
0
1
6
.
1
5
Only like units combine. Seven tenths and four tenths make eleven tenths, which trades for one whole and one tenth, exactly the way ten ones trade for a ten.
2The Ends Do Not Line Up
Lining up the last digits works for whole numbers. With decimals it can put 3.4 in the tenths and hundredths places, which reads it as 0.34.
3Give It a Point, Give It Zeros
8 = 8.00
the point is after the ones,
even when it is not written
Every whole number has a decimal point after its ones digit. Zeros written after the decimal point fill the empty places and do not change the value: 8 = 8.0 = 8.00.
4Estimate to Check
12.75 + 3.4 ≈ 13 + 3 = 16 → 16.15 ✓
8 − 2.35 ≈ 8 − 2 = 6 → 5.65 ✓
13.09 is far from 16, which shows the columns were not lined up.
Round to whole numbers first, then read the answer back against it.
