Puzzle 5
Billy has twice as many sisters as brothers.
His sister, Frankie, has one more sister than she has brothers.
How many boys and girls are there in the family?
Puzzle 6
Starting with SOFT, change one letter at a time until you have the word LENS.
Each change leaves the other letters in their original places and must result in a proper word.
What is the minimum number of steps required to achieve this change?
SOFT
....
....
....
LENS
Puzzle 7
Can you make this equation correct by moving exactly one matchstick?
Note: this puzzle is not interactive, and the matchsticks cannot be moved. The matchstick layouts for each digit are:
Puzzle 8
A Proof That 2 = 1. Let A = B:
A = B
multiply by A on both sides:
A x A = A x B
subtract B x B from both sides:
A x A − B x B = A x B − B x B
factorise:
(A + B)(A − B) = B(A − B)
divide by (A − B) on both sides:
(A + B) = B
replace A with B:
B + B = B
factorise:
2B = B
divide by B on both sides:
2 = 1
Where lies the flaw in the logic?