You know that the time must be 53. something for the second lap. If the total of the first and second lap is a whole number, then all you need do is add something to 0.495 to get a whole number.
Method
What you have to do is add 1 - 0.495 to get the decimal to add to 53.
1 - 0.495 = 0.505 which will give you a whole number.
