Question 12 Marks
Find the L.C.M. of $140$ and $168.$ Use the L.C.M. obtained to find the H.C.F. of the given numbers.
Answer
View full question & answer→Numbers are $140$ and $168$
L.C.M. of $140$ and $168$
$=2 \times 2 \times 7 \times 5 \times 6=840$
$\text { H.C.F. }=\frac{1 \text { st number } \times 2 \text { nd number }}{\text { L.C.M. }}$
$=\frac{140 \times 168}{840}$
$=28$
L.C.M. of $140$ and $168$
| $2$ | $140,$ | $168$ |
| $2$ | $70,$ | $84$ |
| $7$ | $35,$ | $42$ |
| $5,$ | $6$ |
$\text { H.C.F. }=\frac{1 \text { st number } \times 2 \text { nd number }}{\text { L.C.M. }}$
$=\frac{140 \times 168}{840}$
$=28$
