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help! |
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#1
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![]() jellyfishing, jellyfishing ![]() ![]() ![]() ![]() ![]() ![]() Group: Member Posts: 1,174 Joined: Oct 2004 Member No: 55,185 ![]() |
aaacch i don't get this math problem, i'm really stupid. it's a junior high problem, so maybe someone could help?
Claire finished her assignment early, so her teacher suggested that she find the last digit of the product 3 x 3 to third power x 3 to fifth......x 3 to nineteenth. The entire product was too big for her calculator, but she still found the last digit. What is the last digit? Explain how she determined her answer i know that if you add all the exponents, you'll get 3 to the 100th power, since 3+5+7+9+11+13+15+17+19=100 right (those are the exponent values...), so it'd be 3 to the 100th power. on my calc i got 5.153775207 to the 47th power.....what next?!?!!? sorry if this is in the wrong board...i saw someone ask for math help awhile back, so i figured it'd be OK ![]() |
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#2
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![]() :hammer: ![]() ![]() ![]() ![]() ![]() ![]() ![]() Group: Staff Alumni Posts: 9,849 Joined: Mar 2004 Member No: 7,700 ![]() |
I think the last digit is going to be 1.
Because uh.. for every even number exponent, the last digit changed from 1 to 9. 3^2 = 9 3^4 = 81 3^6 = 729 3^8 = 651 3^10 = 59049 3^12 = 531441 So I wrote all the even numbers up to 100 and basically patterned it out. Haha. BUT all the exponents divisible by 4 have a last digit of 1. And 100 is divisible by 4 so the last digit should be 1. |
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