Simplify

a.0.03*0.05
b.4.96/0.004
c.0.01*4*0.5
d.20.74+0.674+0.9

a) 0.0015 
Because 3x5=15
After decimal how many numbers are more=2+2=4
Answer will have 4 digit after decimal.
b) 1240
4.96/0.004
We know that we can cancel decimal if there are equal places after decimal.
4.960/0.004=4960/0004
c) 0.020
Try the method yourself.
d)22.314