We know that

**
LCM
**
**
= Number which gives remainder 0 when dividing by 2, 4, 6
**

Since LCM gives remainder 0

LCM + 7 will give remainder 0

So, Required Number = LCM + 7

LCM of 2, 4, 6 = 12

Required Number = LCM + 7

= 12 + 7

**
= 19
**

Same concept is used in Example 14 and Ex 3.7.4