The Rule of 72 gives them a time frame, assuming certain inflation rates, so that they can look carefully at alternatives and make plans. Pat Taylor has two young children to raise. Pat is very concerned about the impact inflation will have on the purchasing power of her child support dollars. By then her youngest child will be in school all day and Pat plans to be working full time. If she cannot find full time employment, she may consider asking for an adjustment in child support payments.
Courts have, under some circumstances, adjusted child support payments to compensate for inflation.
The Rule of 72 also can be used to predict how long it will take an investment to double in value. However, you have not taken into account what inflation has done to those dollars. Those dollars are called nominal dollars. Select what you believe will be the average annual inflation rate. Now, try the Rule of 72 on an investment problem.