Decimals

What are Decimals?

Decimals are numbers with a decimal point that separate whole numbers from fractional parts. They extend the place value system to the right of the decimal point.

Decimal Place Value

Ones	.	Tenths	Hundredths	Thousandths
3	.	7	4	2

In 3.742:

• 7 = tenths (7/10)
• 4 = hundredths (4/100)
• 2 = thousandths (2/1000)

Comparing Decimals

Compare digit by digit from left to right:

• 0.35 vs 0.309: both have 3 tenths, but 0.35 has 5 hundredths vs 0 hundredths in 0.309, so 0.35 > 0.309

Adding and Subtracting Decimals

Line up the decimal points and add zeros if needed:

  2.70
+ 1.45
------
  4.15

Multiplying Decimals

Ignore the decimal point, multiply, then count total decimal places:

• 0.6 × 0.4 → 6 × 4 = 24, then 2 decimal places → 0.24

Dividing Decimals

Move the decimal point right to make the divisor a whole number:

• 3.6 ÷ 0.4 = 36 ÷ 4 = 9