1 * 3 * 5 + 2 * 6 * 10 + 3 * 9 * 15 =? (simple operation)

1 * 3 * 5 + 2 * 6 * 10 + 3 * 9 * 15 =? (simple operation)


1*5*3+2*2*3*2*5+1*3*3*3*3*5
=1*3*5+8*3*5+27*3*5
=15*(1+8+27)
=15*36
=540