Round off 3678 to the nearest hundred. 

The given number is 3678.

We have to round it off to the nearest hundred,

so if the tens digit is 5 or more, increase the hundreds digit by 1 and replace each digit on its right with 0. 

but if the tens digit is less than 5, the hundreds digit remains the same and replaces each digit on its right with 0.

In 3678, the digit at ten's place is 7 which is more than 5.

Therefore, rounding off 3678 nearest to the hundred is 3700.