The Total solution for NCERT class 6-12
Answer - 11 : -
We know, if a number is composite, then it means it has factorsother than 1 and itself. Therefore,
Given
7 × 11 × 13 + 13
Taking 13 as common factor
We get,
=13(7×11×1+1) = 13(77+1) = 13×78 = 13×3×2×13
Hence, 7 × 11 × 13 + 13 is a composite number.
Now let’s take the other number,
7 × 6 × 5 × 4 × 3 × 2 × 1 + 5
Taking 5 as a common factor, we get,
=5(7×6×4×3×2×1+1) = 5(1008+1) = 5×1009
Hence, 7 × 6 × 5 × 4 × 3 × 2 × 1 + 5 is acomposite number.
There is a circular path around a sportsfield. Sonia takes 18 minutes to drive one round of the field, while Ravi takes12 minutes for the same. Suppose they both start at the same point and at thesame time, and go in the same direction. After how many minutes will they meetagain at the starting point?
Answer - 12 : -