Brain Out Level 100

Overview

The prompt asks an age puzzle: when Zoe was six years old, Lulu was twice her age. Zoe is ten years old now; how old is Lulu? The board has an Enter field and an OK button, with no objects to rearrange. The trap is to keep doubling Lulu's current age, but the doubling only described the age gap at that earlier time. Age differences stay fixed, so the solution is to find the six-year gap and add it to Zoe's current age. Lulu is sixteen.

• Difficulty: Easy
• Estimated moves: 1

Step-by-Step Solution

1. Read the question carefully and separate the two time periods it describes. In the past, Zoe was six years old; in the present, Zoe is ten. The age comparison between the girls belongs to the past period.
2. Work out Lulu's age back then. When Zoe was six, Lulu was twice that age, which makes Lulu twelve at that time. Write those two past ages side by side to keep the timeline clear.
3. Work out the age gap between the two children. Lulu's twelve years minus Zoe's six years gives a six-year difference. This gap is the stable number the rest of the calculation depends on.
4. Recognize that this gap does not change as the years pass. Lulu will always be six years older than Zoe, even though she was twice Zoe's age when they were small. Both children age by the same number of years between the two periods.
5. Fast-forward to now: Zoe is ten years old. Add the fixed six-year gap to Zoe's current age: ten plus six equals sixteen. Four years have passed since Zoe was six, and Lulu has aged by those same four years, from twelve to sixteen.
6. Do not double Zoe's current age. That would produce twenty, but the twice figure belonged only to the earlier comparison and does not repeat every year.
7. Tap the Enter field, type 16, and press OK to submit. The level accepts sixteen as Lulu's current age and shows the success panel.

Strategy & Reasoning

The puzzle separates ratio from difference. At age six, twice means twelve, but that ratio was tied to that particular moment. Once both children age by the same number of years, the ratio shrinks while the difference remains constant. Calculating the gap first protects you from the tempting wrong answer of doubling ten, which assumes Lulu keeps being twice as old forever.

Walking through the timeline makes the reasoning concrete: Zoe six, Lulu twelve; four years later Zoe ten, Lulu sixteen. Both ages rise by four, so the six-year difference survives. The entry field expects a plain number, and no gesture or hidden object is involved. Checking the subtraction before typing confirms the gap, after which the addition to the current age is straightforward.

Tips & Common Mistakes

• Do not answer twenty by doubling Zoe's current age; the "twice" comparison applied only when Zoe was six.
• Calculate the age gap first: twelve minus six is six, and that six-year difference stays fixed.
• Add the gap to Zoe's current age (ten plus six) and enter 16; if the answer is rejected, recheck the timeline rather than trying other multiples.