First we find the common factors. 4 goes into both of these numbers so divide each by 4:
39690051 and 187504375. There are no more common factors so the LCM is:
4×39690051×187504375.
One way to work this out is to write it as:
4(39690000+51)(187500000+4375)=
4(100000000(3969×18750)+10000(3969×4375+51×18750)+51×4375)=
4(100000000(74418750)+10000(17364375+956250)+223125)=
4(100000000(74418750)+10000(18320625)+223125)=
4×
7441875000000000+
183206250000+
223125=
4×
7442058206473125=
29768232825892500 is the LCM.
Another way is to spot that 4×187504375=750017500. So the multiplication becomes:
39690051×750017500, which is easier to multiply:
100(39690000+51)(7500000+175)=100(297675000000000+10000(3969×175+51×750)+51×175)=
100(297675000000000+10000(732825)+8925)=
100×
297675000000000+
7328250000+
8925=
29768232825892500 is the LCM.