Easy computations for the new Mumbai autorickshaw fare

The old tariff for Mumbai's autorickshaw was quite easy to  compute mentally. At least for the regular fare - the late-night fare (after midnight was a different matter), but at least it was easy with the regular fare. So a meter reading of 3.40 could be translated into the fare by multiplying the meter reading by 10  and subtracting 1. Thus, 3.40 on the meter reading would be (3.40 x 10) - 1 = Rs. 33. That's it. No need to carry copies of tariff cards.

The new tariff which came into effect some time in 2010 is a bit more difficult to compute mentally. The official computation is as follows: Rs. 11 for the first 1.00 on the meter, and Rs. 13 for every 1.00 thereafter. A little common sense (read maths) shows that it is still possible to translate this to a formula that can be used to compute the fare mentally. Of course, one needs to know the 13 multiplication tables quite well.

Here is how I do it. Once you get the hang of it, its possible to do it quite fast. I usually try and pronounce the fare before the rickshaw driver can check his tariff card. A couple of rickshaw drivers were surprised by the accuracy of my calculations. I try to practice this quite often now just to check my computation.

The rule is quite simple: Multiple the meter reading by 13 and subtract 2.

• So a meter reading of 3.00 would be (3 x 13) - 2 = 37. And so on.
• Things start to get tricky when we do not have whole meter readings. For example, 3.70. Its still doable, but requires some addition as well. Here's how  to do it:
• First multiply the non-factional  part by 13. This gives 3 x 13 = 39
• Then, multiply the fractional part by 13 and divide by 10. This gives 7x 13/10 = 9.1
• Add both rounding off the resultant. 39+9.1 = approx 48 (rounded off)
• Subtract 2 to get the fare. This gives 48 -2 = 46

Try it out.