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DMAS Rule

There is a rule to follow to solve such numerical expressions that have more than one operations.

Operations are performed in the following order to solve numerical expressions:

First ‐ division

Second ‐ multiplication

Third ‐ addition

Fourth ‐ subtraction

Here are the first letters of the operations in the order in which they are performed.

Remember the sequence by the statement: Dear Mother And Sister.

Now let us solve the expression 5 + 8 + 45 ÷ 5 × 4 – 1 using the rule of DMAS.

5 + 8 + 45 ÷ 5⨯4 – 1
= 5 + 8 + (45 ÷ 5) ⨯ 4 – 1 First - Division
= 5 + 8 + (9 ⨯ 4) – 1 Second - Multiplication
= (5 + 8 + 36) – 1 Third - Addition
=49 – 1 Fourth - Subtraction
= 48

Answer: 48

Remember: If any operation is missing skip to the next operation.

Exercise 3.1

Simplify

  1. 15 + 12 + 14 − 23
  2. 24 ⨯ 15 ÷ 5
  3. 72 ÷ 9 ⨯ 13
  4. 50 − 36 ÷ 6 ⨯ 20
  5. 28 ÷ 7 ⨯ 30 + 6 − 5
  6. 108 ÷ 12 ⨯ 15 − 10

Brackets

Solve the bracket in a numerical expression first no matter which operation it has.

Example 1:

Solve 4 ⨯ 12 + (8 ⨯ 2) ÷ 2
4 ⨯ 12 + (8 ⨯ 2) ÷ 2 = 4 ⨯ 12 + 16 ÷ 2 Solve the bracket first

Now follow the rule of DMAS to solve the expression further.

4 ⨯ 12 + 16 ÷ 2 Divide
= 4 ⨯ 12 + 8 Multiply
= 48 + 8 Add
= 56
Answer:56

Exercise 3.2

Solve

  1. 3 ⨯ (5 + 4)
  2. 7 + (9 ÷ 3)
  3. 14 − (3 ⨯ 4)
  4. 5 + (7 − 3) ⨯ 10
  5. 9 − ( 5 ⨯ 1) + 4
  6. 6 + (10 ÷ 2) − 7

Exercise 3.3

Story sums on numerical expression

Example:

Raj has 4 sets of 5 stamps. He gave 6 stamps to Sanjay. How many stamps are left with Raj now?

Raj has 4 sets of 5 stamps = 4 ⨯ 5

He gave 6 stamps to Sanjay = (4 ⨯ 5) – 6

Now solve the expression.

(4 ⨯ 5) – 6 = 20 – 6
= 14

Raj has 14 stamps left with him.

Write the numerical expression for the following word problems and solve it.

  1. Ajay bought 5 brown eggs and 6 white eggs for his bakery. Accidentally he dropped 3 eggs. How many eggs are left with him?
  2. There were 15 rows of 12 chairs in an auditorium. 22 more chairs were placed randomly. How many chairs are there in the auditorium?
  3. Cost of a toy train was ₹120. But after discount, it was on sale for ₹99. What amount Mrs Sinha has to pay if she buys 7 toy trains for her kindergarten?
  4. Meenal has ₹100 note. She bought ice cream for ₹24 and a bar of chocolate for ₹40. How much money is left with her?
  5. Ramu gets ₹200 as his daily wage. At the end of the month, he received ₹800 as a bonus. How much money did he receive at the end of the month?