Decimals · Usually met around P4
Decimals and fractions
Tenths are 110, hundredths 1100.
How to do it
Method
Tenths are 1/10, hundredths 1/100
0.37 = 37100 = 310 + 7100
Another way
A number line
0 to 1 in 10 steps: the 3rd step is 0.3
In full
Cut 1 into 10 equal parts: each is 110, written 0.1. Into 100 parts: each is 1100, or 0.01. Into 1000: each is 0.001. So 0.3 = 310, 0.37 = 37100 = 310 + 7100, and 0.07 = 7100. With a picture, count all the parts first, then the shaded ones: 37 of 100 squares shaded is 0.37. Or use a number line: 0 to 1 cut into 10 steps, the 3rd step is 0.3. Careful: 0.7 and 0.07 differ, since a 7 in the tenths is 710 and in the hundredths 7100.
Worked examples
Have a go first, then open each one for the answer and the working.
Example 1
This rectangle is cut into 10 equal parts. As a decimal, how much is shaded?
Show the answer and working
Answer: 0.1
Each part is 110 = 0.1, and 1 are shaded: 110.
Example 2
On the number line, 5 to 6 is cut into 10 equal steps. What number does the arrow point to?
Show the answer and working
Answer: 5.2
Each step is 0.1; 2 steps from 5 is 5.2.
Example 3
Which decimal is 4100?
- A. 0.4
- B. 0.04
- C. 4
- D. 0.004
Choose the right answer
Show the answer and working
Answer: B. 0.04
4100 is 4 hundredths: 0.04.
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