 # Simple Algebraic Substitution with Decimal Numbers

In this worksheet, students substitute decimal numbers for letters and work out the value of simple expressions with one variable. Key stage:  KS 3

Curriculum topic:   Algebra

Curriculum subtopic:   Substitute Numerical Values for Formulae/Expressions

Difficulty level:   ### QUESTION 1 of 10

When we substitute a number for a letter, we simply replace the letter with the number.

However, we must remember that 4b means 4 x b.

Example

Work out the value of the following expression when a = 0.4

3a - 1

3a - 1

= 3 x a - 1

= 3 x 0.4 - 1

= 1.2 - 1

= 0.2

Work out the value of the following expression when a = 0.1

2a + 5

Work out the value of the following expression when a = 0.2

2a + 6

Work out the value of the following expression when a = 4.4

2a - 7

Work out the value of the following expression when a = 2.7

a + a

Work out the value of the following expression when a = 1.5

5a + 2

Work out the value of the following expression when a = 0.8

2 - 2a

Work out the value of the following expression when a = 0.4

10 - 2a

Work out the value of the following expression when a = 9.9

20 - a

Work out the value of the following expression when a = 5.6

20 + 2a

Work out the value of the following expression when a = 0.75

20 + 2a

• Question 1

Work out the value of the following expression when a = 0.1

2a + 5

5.2
• Question 2

Work out the value of the following expression when a = 0.2

2a + 6

6.4
• Question 3

Work out the value of the following expression when a = 4.4

2a - 7

1.8
• Question 4

Work out the value of the following expression when a = 2.7

a + a

5.4
• Question 5

Work out the value of the following expression when a = 1.5

5a + 2

9.5
• Question 6

Work out the value of the following expression when a = 0.8

2 - 2a

0.4
• Question 7

Work out the value of the following expression when a = 0.4

10 - 2a

9.2
• Question 8

Work out the value of the following expression when a = 9.9

20 - a

10.1
• Question 9

Work out the value of the following expression when a = 5.6

20 + 2a

31.2
• Question 10

Work out the value of the following expression when a = 0.75

20 + 2a

21.5
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