Page 160 - Start Up Mathematics_6

Example 2: Write the following decimals in the place value table.

(a) 23.1 (b) 0.8 (c) 603.8
Solution: 1
Hundreds (100) Tens (10) Ones (1) Tenths
10
(a) 0 2 3 1

(b) 0 0 0 8
(c) 6 0 3 8

Example 3: Write each of the following as decimals:
(a) Four-tenths (b) Three tens and nine-tenths (c) Fourteen point eight

(d) Two hundred and three ones (e) Four hundred point seven

4  1 
Solution: (a) = 0.4 (b) 3 × 10 + 9 ×   = 30 + 0.9 = 30.9
10  10 
(c) 14.8 (d) 203.0 (e) 400.7
Example 4: Write each of the following as decimals:
7 34 9 2 1
(a) (b) (c) (d) 6 (e) 800 + 70 + 5 +
10 10 2 5 10
7
Solution: (a) = 0.7
10
34 30 + 4 30 4
(b) = = + = 3 + 0.4 = 3.4
10 10 10 10
9 9 × 5 45 40 + 5 40 5
(c) = = = = + = 4 + 0.5 = 4.5
2 2 × 5 10 10 10 10
2 2 2 × 2 4
(d) 6 = 6 + = 6 + = 6 + = 6 + 0.4 = 6.4
5 5 5 × 2 10
1 1
(e) 800 + 70 + 5 + = 875 + = 875 + 0.1 = 875.1
10 10
Example 5: Write the following decimals as fractions. Reduce the fractions to the lowest form.

(a) 0.2 (b) 1.0 (c) 7.4 (d) 14.7

2 1 0 10 0 10
Solution: (a) 0.2 = = (b) 1.0 = 1 + = + = = 1
10 5 10 10 10 10
4 70 4 74 37 7 140 7 147
(c) 7.4 = 7 + = + = = (d) 14.7 = 14 + = + =
10 10 10 10 5 10 10 10 10

Example 6: Express the following as cm using decimals.
(a) 3 mm (b) 55 mm (c) 212 mm (d) 5 cm 2 mm
1
Solution: We know, 1 cm = 10 mm or 1 mm = cm

3 10
(a) 3 mm = cm = 0.3 cm
10

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