稻田要畫上大大的彩繪圖，孩子幫農夫算出要插多少秧苗。每一題先在數線上拖稻草人估一估答案大約多少（例如 2.3 × 1.4 大約是 2 × 1.5 = 3），乘法機器再把小數當成整數算好（23 × 14 = 322），孩子把小數點拖到數字中間，放成 3.22，和剛剛的估計對一對。第 1 關是整數和小數相乘，第 2 關是小數乘以小數（有 0.3 × 0.4 = 0.12 這種要補 0 的），第 3 關先猜乘出來會比原來的數大還是小，再放小數點。
適合年級：五年級（約 10～11 歲）。對應 108 課綱（十二年國教）數學單元：五年級「小數乘法（直式）」。各版本教科書的單元順序不同，完整對照請看國小數學課綱對照表。免費、無廣告、不用註冊，手機、平板、電腦打開就能玩，題目有注音，也會念出來。
陪玩小提醒：兩個數一共有幾位小數，積就有幾位小數；算完用估算檢查，就不會把 3.22 寫成 32.2。也可以問問孩子：3.6 × 0.5 為什麼比 3.6 小？
A rice paddy is getting a giant painted picture, and children help the farmer with the sums. For each one they first drag the scarecrow along a number line to estimate (2.3 × 1.4 is about 2 × 1.5 = 3); the multiplying machine then works it out as whole numbers (23 × 14 = 322), and children drag the decimal point between the digits to make 3.22 and compare it with their estimate. Level 1 multiplies whole numbers and decimals, level 2 decimals by decimals (including answers like 0.3 × 0.4 = 0.12 that need extra zeros), and level 3 asks first whether the answer is bigger or smaller than the starting number.
Suits Grade 5 (about age 10–11) in Taiwan. Taiwan curriculum (12-year basic education) unit: Multiplying decimals (column method) (Grade 5). Free with no ads and no sign-up, in Traditional Chinese with zhuyin and in English, read aloud. See the Taiwan elementary maths curriculum map.