☰ Year plan · Mathematics

Tenths, hundredths and place value

Week 20 · Tenths, hundredths and place value · 3 lessons
2

Ten tenths, one hundred hundredths

Discover Mathematics P4: Term 2, Unit 10, Lessons 1–4
GoalWrite hundredths as fractions and as decimals, and see that 10 hundredths make 1 tenth.
New words
hundredth · one of 100 equal parts of a whole; 1/100 = 0.01hundred grid · a square cut into 100 equal small squaresequivalent decimals · decimals with the same value, such as 0.3 and 0.30
Explanation

Cut a whole into 100 equal parts and each part is one hundredth: 1/100 = 0.01. The first digit after the point is the tenths and the second is the hundredths. So 23/100 = 0.23, which is 2 tenths and 3 hundredths. 7/100 = 0.07, with a 0 in the tenths place because there are no tenths. Careful: 0.07 is not 0.7. Ten hundredths make one tenth, because a tenth column on the hundred grid has 10 small squares. So 0.10 = 0.1 and 30/100 = 3/10, which means 0.30 = 0.3. A tenth is ten times as big as a hundredth. Reading: 0.23 is twenty-three hundredths.

Worked examples
What decimal is shaded on the grid? 2 full columns are 20 squares and 3 more squares are shaded, 23 squares of 100. 23/100 = 0.23, which is 2 tenths and 3 hundredths.
Write 7/100 as a decimal. Only 7 small squares are shaded, so there are no whole columns (no tenths): 0 tenths and 7 hundredths. 7/100 = 0.07.
Show that 0.3 = 0.30. 3 tenths are 3 full columns of 10 squares, which is 30 squares of 100. So 3/10 = 30/100 and 0.3 = 0.30.
Class activity

Make a hundred grid. On squared paper draw a 10 by 10 square. Colour 0.35 of it (3 columns and 5 squares). Then colour 0.08 on another grid. Say each as a decimal and a fraction.

Practice
1
Write 47/100 as a decimal.
2
Write 0.09 as a fraction.
3
Write 60/100 as a decimal in two ways. What is 60/100 as a fraction with denominator 10?
4
How many hundredths are in one tenth?
5
Seif writes 7/100 as 0.7. What is wrong? Write it correctly.