25/336 +2/132 =( 25*11+2*28)/3696=(275+56)/3696=331/3696
336 =2⁴x3x7
132=2²x3x11
cmmmc=2⁴x3x7x11=3696
3/345 - 7/546=(3*182-7*115)/62790=(546-805)/62790=259/62790
345=3x5x23
546=2x3x7x13
cmmmc=2x3x5x7x13x23=62790
1/2013 +1/2016=(672+671)/1352736=1343/1352736
2013=3x11x61
2016=2⁵x3²x7
cmmmc=2⁵x3²x7x11x61=32*9*77*61=1352736