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Decimals

Decimals are how we write numbers between the whole ones — using the same place value system, just continuing past the dot.

Hundred-square decimals

1 small square = 1 hundredth

0.37

(37/100 of the square)

Hundredths

37

Jump 10s

3

3 tenths + 7 hundredths

Past the decimal point

Place value doesn't stop at the ones column. Cross the decimal point and the columns keep going, but each one is now ten times smaller.

  • The first column after the dot is tenths (1/10).
  • Then hundredths (1/100).
  • Then thousandths (1/1000), and on it goes.

Reading 0.37

0.37 means 3 tenths and 7 hundredths. Or said another way: 37 hundredths — 37 of the 100 little squares above.

Lining up the dot

When adding or subtracting decimals, line the dots up first. That keeps tenths under tenths and hundredths under hundredths — so the place values match.

Common conversions

  • 1/2 = 0.5
  • 1/4 = 0.25
  • 3/4 = 0.75
  • 1/10 = 0.1

Quick check

  1. What does the 4 in 0.84 represent?
  2. Which is bigger, 0.6 or 0.59?
  3. Add: 0.3 + 0.45.

Answers: 4 hundredths, 0.6 (six tenths beats five tenths), and 0.75.