Anchor Chart · Grade 5 · 5.NBT.B.7
Adding and Subtracting Decimals
Tenths join tenths. Hundredths join hundredths. The point is what keeps them honest.
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
Pushing the ends flush is a whole number habit. It slides 3.4 into the tenths and hundredths and quietly turns it into 0.34.
3Give It a Point, Give It Zeros
8 = 8.00
the point hides
after the ones
Every whole number already owns a point. Trailing zeros fill the empty places and change nothing: 8 = 8.0 = 8.00.
4Estimate Before You Believe It
12.75 + 3.4 ≈ 13 + 3 = 16 → 16.15 ✓
8 − 2.35 ≈ 8 − 2 = 6 → 5.65 ✓
13.09 is nowhere near 16. A missed estimate is the columns telling on you.
Round to whole numbers first, then read the answer back against it.
