+426 Help me in Math Olympiad, the contest is on April 6!!!!
How many consecutive zeroes are at the end of:
a) 10!
b) 14!
c) 20!
d) 25!
+426 The calculator will show up results like:
x × 10y or some errors that go above 9.999999999999999 × 1099
Also calculators are NOT allowed in the contest of Math Olympiad.
+426 When I try using a calculator, my calculator calculates only ranges of:
± 1 × 10-99 ≤ x < 1100 or 0.
The maximum factorial used for my calculator is:
69 !
+118687 a) 10!
1*2*3*4*5*6*7*8*9*10
1*2*3*4*5*6*7*8*9
one
1*3*4*6*7*8*9
two
1*3 ends in 3
3*4 ends in 2
2*6 ends in 2
2*7 ends in 4
4*8 ends in 2
2*9ends in 8
so the last 3 digits are 800
that is 2 zeros at the end.
b) 14!
10! ends in 800
11! ends in 800
12! ends in 600
13! ends in 800
14! ends in 200
c) 20!
15! ends in 000
20! ends in 0000 4 zeros
d) 25!
1*2*3*4*5 has 0ne zero at the end
so add another zero
25! 5 zeros
