Find the L.C.M. and H.C.F. of the following pairs of integers and verify that L.C.M. × H.C.F. = product of two numbers.

(i) 26 and 91

(ii) 510 and 92

(iii) 336 and 54

Find the L.C.M. and H.C.F. of the following integers by applying the prime factorisation method.

(i) 12, 15 and 21

(ii) 17, 23 and 29

(iii) 8, 9 and 25

Check whether 6ⁿ can end with the digit 0 for any natural number n.

Explain why 7 × 11 × 13 + 13 and 7 × 6 × 5 × 4 × 3 × 2 × 1 + 5 are composite numbers.