Before dealing with the specifics of the rules for determining the significant figures in a calculated result, we need to be able to round numbers correctly. To round a number, first decide how many significant figures the number should have. Once you know that, round to that many digits, starting from the left. If the number immediately to the right of the last significant digit is less than 5, it is dropped and the value of the last significant digit remains the same. If the number immediately to the right of the last significant digit is greater than or equal to 5, the last significant digit is increased by 1.
Matt was trying to stick to a budget at the grocery store so he estimated what he was spending as he went along. He grabbed some milk for $3.45 and $3.50 to his total. When picked up cookies for $2.03 he added $2 to his total.
How many signifigant number were in the milk price?