2014-08-18

175. Consecutive zeros


When the integers from 1 to 30 are multiplied, determine how many consecutive digits starting from the ones (1s) position are zeros.

2014-08-11

174. Triangle on graph paper

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In the diagram, two straight lines are drawn on a 1 cm grid.
Determine the area of △ABC.

(from Twitter)

2014-08-04

173. Peppers, carrots and spinach

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100 students were surveyed about their preferences for bell peppers (capsicum), carrots and spinach, with the following results:

①  72 students said they like bell peppers, and 36 students said they like only bell peppers.
②  41 students said they like carrots, and 9 students said they like only carrots.
③  31 students said they like spinach, and 3 students said they like only spinach.
④  9 students said they like neither bell peppers, nor carrots, nor spinach.

Answer the following questions:
⒜  Amongst bell peppers, carrots and spinach, determine how many students like 2 or more.
⒝  Determine how many students like both carrots and spinach, but not bell peppers.