Numbers & Place Value

Explore large and small numbers and discover how place value works – interactively. This is not a drill app but an open environment for exploring and experimenting. Understanding place value is one of the most important foundations in mathematics: it underpins mental and written calculation strategies, decimals and much more. HOW IT WORKS Drag the digits up and down with your finger. Go beyond 9 and watch ten items bundle into one item of the next place. Go below 0 and see how the next place is "unbundled". Swipe or tap the quantity below a digit to change it. At the bottom of the screen, choose how the quantity is shown: place value counters, base-ten (Dienes) blocks, euro money, dot fields, 3D base-ten material and more. TOOLS ON THE RIGHT - Speaker: listen to the number being read aloud. - Speech bubble with check mark: read the number aloud yourself and check whether you read it correctly. - Expand: shows, for example, 142 as 100 + 40 + 2. - Dice: roll a random new number. - Speech bubble with dots: say a number and watch it appear. - Question mark: some places are covered, the number is read aloud and you fill in the missing digits. MORE OPTIONS - Use the grey arrows to add or remove places – explore numbers up to 100 trillion. - Move the decimal point to work with decimals down to millionths. - Tap a place label (O, T, H …) to change its color. - Swipe across a digit to cover it; tap the cover to enter your answer and get feedback. - Number words above the digits in matching place colors – optionally as "Say Ten" number words (e.g. 284 = "two hundred eight ten four"). - Many settings in the app: thousands separator, place labels, speech rate, show or hide tools and representations, protect settings. - Share a setup or task with your class via QR code. - English (UK/US) and German. - Also available in the browser: zahlen.urff.app IDEAS FOR THE CLASSROOM - Number dictation: show 3,469. - Keep adding one to the ones. What happens when you go past 9? - Show 340. What happens when you take one away from the ones? What about 300? - Show 5,216 and expand it: which numbers make it up (5,000 + 200 + 10 + 6)? What about 5,316? - Listen to a number, then change one place. Can you read the new number correctly? - Tap the question mark and solve some tasks – the app counts them for you. - Why does the leading zero in 0453 disappear? Why does the zero stay in 204 or 240?