I was buying something this afternoon and the total rang up as 1.70. I only had 50 cents in change, so I had to give the cashier two bucks. I got the thirty cents back and I'm looking at it in my hand and thinking "well, NOW I have enough coins" and I thought I remembered someone saying that when this situation comes around, it seems like you always wind up with enough coins for the transaction after it's over. I thought I'd figure it out to be sure, and not that it's all that interesting, but here's what I found.

If you've got no coins and the amount you need is less than fifty cents, you'll obviously wind up with enough afterward and this is not so if the amount you need is over fifty cents. This could become tedious if I don't do this according to a system, so I'm going to put the amount of change you have and the maximum amount you would be able to make change for after the transaction, based on those amounts. (You'll wind up with .75 after the transaction if you started with .50 but not .76)

0 50
5 52
10 55
15 57
20 60
25 62
30 65
35 67
40 70
45 72
50 75
55 77
60 80
65 82
70 85
75 87
80 90
85 92
90 95
95 97

As you can see, if you have an amount of change and you divide the amount between it and a hundred by two, then add that to your amount and ignore the decimal points, you get your answer, so fifty per cent of the time you wind up with each scenario.


At Friday, January 05, 2007, Anonymous robinkisser said...

Ha! I was right. Thanks for the shout out by the way.

At Saturday, January 06, 2007, Blogger dale said...

You mean the shout out I didn't give you?


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