Question

find the no. of significant figures in
1) 5418000
2) 2.63*10^26

Answer 1

in 1. there are 4 significant figures and in 2. there are 3 significant figure

Answer 2

The term significant figures refers to the number of important single digits in the coefficient of an expression in scientific notation . 

So, the answer is.
There are 4 significant figures in the 1st one (5,4,1,8)
And 3 in the 2nd one(2,6,3)