Solved Examples on Subtraction Formulas

Example 1: If Ram’s mother gave him 99 rupees to buy stationary, out of which he used 60 rupees. Then calculate the amount he left with.

Solution:

Total amount of money he has 99 rupees,

He spends 60 rupees.

Now, he left with (99-60) rupees = 39 rupees.

Example 2: Find the difference between 454 and 666.

Solution:

The difference between 454 and 666 is given by,

454 – 666 

= – (666 – 454) 

= -212

Example 3: If there are 67 apples and a dozen of Apples are distributed among some children. How many apples are there? 

Solution:

As we know 1 dozen = 12 units

So 12 apples have been distributed

Therefore the number of apples is 67 – 12 

= 55

Example 4: How much we should subtract from 1000 to get 90? 

Solution:

Let x be the subtrahend, then

1000 – x = 90

Therefore x = 1000-90 

= 910

Example 5: Find the value of 4/2 – 3 -6.

Solution:

According to BODMAS rule, 4/2 = 2

Then 

4/2 – 3 -6 = 2 – 3 – 6 

= -7

Example 6: Find cos 15°.

Solution:

We known that,

cos(a-b) = cosa.cosb + sina.sinb…(i)

Choose a = 45° and b = 30°

cos⁡15° = cos ⁡(45° – 30°)

Using formula from eq(i)

cos⁡15° = cos⁡45°cos⁡30° + sin⁡45°sin⁡30°

Substituting,

• cos⁡45° = 1/√2, and cos⁡30° = √3/2
• sin45° = √2, and sin⁡30° = 1/2

Putting these into the formula:

cos⁡15° = (1/√2)(√3/2) + (1/√2)(1/2)

cos15° = (√6 + √4)/4

Example 7: Find sin 15°.

Solution:

We known that,

sin(a-b) = sina.cosb – cosa.sinb…(i)

Choose a = 45° and b = 30°

sin15° = sin ⁡(45° – 30°)

Using formula from eq(i)

sin15° = sin45°cos⁡30° – cos⁡45°sin⁡30°

Substituting,

• cos⁡45° = 1/√2, and cos⁡30° = √3/2
• sin45° = √2, and sin⁡30° = 1/2

Putting these into the formula:

sin ⁡15° = (1/√2)(√3/2) – (1/√2)(1/2)

sin 15° = (√6- √4)/4

Subtraction is a fundamental arithmetic operation. Subtraction is a mathematical operation that involves subtracting a part of one number from another. The process of subtracting one number from another is known as subtraction.