Hint
Adding 900,000 to the numbner is the same as placing a 9 at the beginning.
Answer
23,076.
Reasoning
Placing the 9 at the beginning is equivalent to adding 900,000 (for example, 12,345 + 900,000 becomes 912,345).
Placing the 9 at the end is equivalent to multiplying by 10 and adding 9 (for example, 12,345 x 10 + 9 becomes 123,459).
Let's call the unknown number k, and we know that one of these numbers is 4 times the other, so:
k + 900,000 = 4 x (10k + 9)
k + 900,000 = 40k + 36
900,000 − 36 = 40k − k
899,964 = 39k
899,964 ÷ 39 = k
Therefore, k = 23,076.
Double-Checking 923,076 = 4 x 230,769.
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Puzzle 115
At the local racetrack, Alex was testing the latest car.
During the eight test laps, Alex managed to average the first two laps at 100mph, the next two laps at 102mph, the next two laps at 140mph, and the last two laps at 150mph.
The 8 laps were 40 miles, and using Speed = Distance ÷ Time: average speed = 40 ÷ (40/119) average speed = 40 x (119/40) = 119 mph
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Puzzle 116
A farmer buys chicken feed for 47c per tonne, pig feed for $1.23 per tonne and cattle feed for $1.44 per tonne. The feed can only be purchased by the tonne, and part tonnes aren't sold.
How much of each would they have if they bought 100 tonnes for $100?
