It seems like you're asking about the cost of three mangoes, with the information "seven91." However, it's unclear what "seven91" refers to. Could you clarify if it represents the price of one mango or something else?

If "seven91" stands for the price of one mango (791 units of currency), the cost of three mangoes would simply be:

$3 \times 791 = 2373$

Thus, the cost of three mangoes would be 2373 units.

Let me know if this is correct or if you'd like further clarification!

Relative Questions:

1. Is 791 the price of one mango or a different quantity?
2. Do you need the cost of mangoes in a specific currency or context?
3. Are there any other items whose costs need to be calculated similarly?
4. Should I include taxes or discounts in the calculation?
5. Are you looking for a formula for general cases?

Tip: Always double-check the units or currency in word problems to avoid confusion in calculations.