# Introductory exercise for the addition of large natural numbers

I'm starting a repetition with my students in 5th grade after they learned in elementary school how to sum up larger natural numbers (also 5- to 6-digits) by writing down that calculation.

As introductory example that has a connection to their every day life, I search for a good exercise that just needs them to add up several natural numbers without being too easy.

I thought about an amusement park where there is a roller coaster and the park needs to calculate the degree of capacity utilization but am lacking a formulation that is consistent and just needs them to add some numbers up, since a decrease of the number of uses forces a subtraction. Do you have a better idea?

• It seems to me that most any computation of an average of a lot of numbers will qualify, so maybe consider some natural examples where they might want to find an average (maybe grades). A possible classroom project might be to find today's average age of your students in days. This could be an hour+ long activity, as leap years, different numbers of days per month, etc. need to be considered. Perhaps the simplest approach would be to determine the youngest person's age in days, then multiply that by the number of students, then add the remaining ages of the students relative to this student. – Dave L Renfro Nov 19 '19 at 7:34

How about: The number of days to their next birthday? This could involve: number of days remaining in this month, plus the number of days in the next month, the next, ..., until the number of days in their birthday month. Or, similarly: The number of days from now until Christmas: $$13$$ in November plus $$25$$ in December: $$13+25=38$$. Capitalizing on their excitement over special days.
Another example is that if you have lets say $$30$$ guests coming to your home, you want to buy cups for the tea or coffee or whatever but these cups come in dozens, i.e. there is only bags of $$12$$ cups, so how many bags you need?
They start for example $$12+12=24$$ not enough cups, $$12+12+12=36$$ now we have enough cups, so we need $$3$$ bags.