CommonDivisor vs Mahoujin

A simple math game for kids who struggle with reducing fractions. Find common divisors among 9 numbers and keep dividing. The rules are easy, but the learning is deep. Players naturally understand why fractions can be simplified. • Build intuition for common divisors • Improve fraction skills through repetition • Learn by playing, not memorizing Perfect for home practice, classrooms, and family play.

Every row, column and diagonal adds up to the same number. That is a magic square. But this app does not just hand you a board. It withholds the target sum, lets your child find it from a line that is already complete, and — when they get stuck — helps in three steps: the line, then the equation, then the answer. ■ It teaches the method first "ときかたを おぼえよう" on the home screen runs a seven-step lesson on a fixed teaching board that uses the same numbers as the first level: 1-9, with a total of 15. It starts by finding a line that already has three numbers and working out the common total (if the line is hard to spot, the "おしえて" button lights it up cell by cell). Progress is saved, so a child can stop and come back to the same step. ■ The total is not given away On the two harder levels the target sum stays hidden, and so does every line total, until your child adds up a complete line and enters what they found. That single move is what turns "a rule someone told me" into something understood by hand. ■ Hints stop at the equation The first press outlines the line to look at. The second shows it as an equation — 7 + ? + 3 = 15. Only the third gives the number. The button label changes from "ヒント" to "もう すこし" to "こたえを みる", so a child can see what the next press will give and choose to keep thinking. Stars are never reduced for using hints. ■ A wrong answer points at a cell, not at the answer When a number is wrong, the app selects the cell to revisit and builds the equation from the neighbouring values that are already correct. A child is never asked to calculate from a mistaken premise. ■ Three levels - First steps: 3 empty cells, target shown. The first three puzzles use 1-9 (total 15); from the fourth on, totals range from 15 to 30 - Normal: 5 empty cells, find the target yourself - Challenge: 5 empty cells, larger numbers Levels open from the bottom up: solving one First steps puzzle opens Normal, and solving one Normal puzzle opens Challenge. On Normal and Challenge, the complete line is always a row or a column. Every board is generated on the device and verified to be solvable one cell at a time — 1,000 puzzles per level are checked automatically. ■ Charms to collect One star per puzzle solved. Eight charms appear as the stars add up, and the title grows with them. Pick which charm sits on the home screen. Colour themes unlock along the way. Charms come only from solving puzzles; there is nothing to buy. ■ Adjustable - Target total: shown, or found by the child (even on First steps, play can start by working out the total) - Line totals: automatic, always shown, or hidden - Next cell: prefer empty cells, or follow position - Motion: match the device, or reduce effects - Sound: off at first. Turn it on with the speaker button at the top right; sound effects then play even when the ring/silent switch is set to silent The rounded Japanese typeface ships inside the app, and text wraps at meaningful breaks. Everything runs on the device, so it works with no signal. ■ Never rushed There is no timer and nothing that counts consecutive days. A child can spend as long as they like on one cell. Ask them not whether they were faster than yesterday, but whether a line that puzzled them yesterday makes sense today. Solved puzzles and collected charms stay on the device. Nothing is sent anywhere. Suggested age: 6 to 8 years old.