Grades 11-12 Video Solutions 2025-2025_11-12

Video Transcription

Video Summary

In the problem from the Math Kangaroo exam for grades 11 and 12, points in a unit square on the xy-plane are painted black if the first digit after the decimal point for both x and y is odd. To systematically determine the pattern, only segments of rows and columns corresponding to odd digits, such as 0.1, 0.3, 0.5, 0.7, and 0.9, are painted. The overlapping intersections of these segments result in a pattern of smaller squares within the unit square, resembling a checkerboard pattern, corresponding to option E from the provided answer choices.

Keywords

Math Kangaroo

unit square

xy-plane

checkerboard pattern

odd digits