Use the digits from 1 up to 9 and make 100.

Follow the rules.
=> Each digit should be used only once.
=> You can only use addition.
=> For making a number, two single digits can be combined (for example, 4 and 2 can be combined to form 42 or 24)
=> A fraction can also be made by combining the two single digits (for example, 4 and 2 can be combined to form 4/2 or 2/4)

Question: how can we do this?

A famous swimmer can swim downstream in a lake in exactly 40 minutes with the lake current.
He can swim upstream in that lake in exactly 60 minutes against the lake current.
The length of the lake is 2 km.

How long he can cover the distance of one side at a still lake with no current?

What is the largest number you can write with just 3 digits?

In a mathematical quiz, you are asked the following question:

Use three 9s in a mathematical expression without dividing or multiplying to form the number one.

Can you answer the question?

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

What is next number in the pattern below:

131 517 192 123 ?

Get total of 120 by using five zeros 0,0,0,0,0 and any one mathematical operator.
Do you ?

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

What three numbers, none of which is zero, give the same result whether they’re added or multiplied?

How many pluses should we put between the digits of 987654321 to get a total of 99, and where?