How many bombers can you buy using 1000 coins ?

Question

In "Clash Royal" App Game, Warrior "The Bomber" is a very good defensive options. It can be purchased from the card shop.The cost of the bomber is quite interesting.The Cost of 1st bomber is: 2The Cost of 2nd bomber is: 4The Cost of 3rd bomber is: 6The Cost of 4th bomber is: 8The Cost of 5th bomber is: 10i.e to buy 5 bombers you need 2+4+6+8+10 = 30 coins.
How many bombers can you buy using 1000 coins ?

Answer 1

62

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The cost of the bomber number y which is even number in the format of 2x will be:
x*(2+2x)/2=x(x+1)<=1000 (the sum of arithmetic progression) , the highest number of x is 31 what gives us 31*32=992
y=31*2=62 will be the max number of bombers under 1000 coins