Riddles, one at a time
Two Candles: 12 cm and 8 cm
After how many hours are they the same height?
Find the gap between the candles, then how much it shrinks each hour.
4 hours
After 4 h: A is 12 − 8 = 4 cm, B is 8 − 4 = 4 cm.
Longest Roman Numeral
Which number from 1 to 99 has the longest Roman numeral, written the usual way?
Which digits need the most letters on their own?
88
88 = LXXXVIII, 8 letters. No other number below 100 has 8.
Two Glass Cards
Slide the two glass cards together. Which number appears?
Imagine the strokes of both cards on one card.
48
Card A's strokes fill the gaps on card B: 4 and 8.
Count Every Cube
27
Column heights, row by row: 4+3+3+1 = 11, 3+3+2+1 = 9, 2+2+1 = 5, 1+1 = 2. Total 27, hidden cubes included.
Fence Posts
A straight 15 m fence has a post every 3 m, with one at each end. How many posts are there?
Count the gaps first, then the posts.
6
15 ÷ 3 = 5 gaps, and 5 gaps need 6 posts.
Flip-Flop Gates
Gates start as shown and flip after each box. Where does box 3 land?
BIN C
After boxes 1 and 2, box 3 goes left, right, right.