Question

What is the greatest 4 digit number which is exactly divisible by 30 and 40 both?

Answer 1

greatest four digit number is 9999

greatest four digit number divisible by both 30 and 40 is 9960.

to find this we will first find the LCM of these two numbers

30 = 2×3×5

40 = 2×2×2×5

LCM = 2×2×2×3×5 =120

Now we will find the greatest four digit number divisible by 120. That number will be divisible by both 30 and 40 .

so after dividing greatest four digit number by 120 we get,

quotient = 9960 with remainder 39

so our final answer will be 9960.

Answer 2

The correct answer is 9600.

Given: Number should be 4- digit and should be exactly divisible by 30 and 40.

To Find: Greatest 4 digit number which is exactly divisible by 30 and 40 both.

Solution:

It means number should be multiple of 30 and 40 both.

We can also say that it should be multiple of 30*40 = 1200.

1200 * 8 = 9600

1200 * 9 = 10800

Hence, 9600 is greatest 4 digit number divisible by 30 and 40 both.

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