🏙️ Skyscraper Numbers

Build big numbers as a city skyline where every place is a building ten times taller than its neighbor.

REMEMBER: In our base-ten system, every place is ten times the place to its right. Ten ones = one ten. Ten tens = one hundred. Ten hundreds = one thousand. All the way to 1,000,000. A digit’s value comes from which place it lives in, not just its face. To compare, walk left-to-right until digits differ. To round, pick a place, then look at the digit to its right: 5 or more → up, less than 5 → stay.

Part 1 · Build the Skyline

Set each place with the +/− buttons. Each building is exactly ten times taller than the one to its right. Load ten little blocks into a place and the crane trades them for one block of the next place up.

Standard form
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Number name
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Expanded form
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Comparison Rounds — two skylines, side by side

Walk left-to-right. The first tower where the buildings differ decides which number is bigger.

Rounding Zipline

Pick a place to round to. The zipline carries the number to the nearer landmark on the number line.

Part 2 · Build-This-Number Challenges

Predict before you build. Lock in an answer, then see the reveal. Every round tests the ten-times structure, reading big numbers, comparing, rounding, or a trade in the algorithm.

Part 3 · The Machines

Three step-by-step machines. Each step says what to do and why.

Read, write, and compare

    Round to any place

      Standard algorithm with trades

        Part 4 · Master Builder Quiz

        Ten questions. Each wrong answer tells you which part to revisit.

        Question 1 of 10 Score: 0

        Word Box

        Place value
        The value a digit has because of where it sits. The 3 in 3,000 is worth 3,000 — a thousand times more than the 3 in 3.
        Ten times
        Each place is 10 times its right-hand neighbor. Ten ones make a ten; ten tens make a hundred.
        Standard form
        Digits in place order, with commas every three places: 342,517.
        Word form (number name)
        The number in words: three hundred forty-two thousand, five hundred seventeen.
        Expanded form
        The number written as a sum of place values: 300,000 + 40,000 + 2,000 + 500 + 10 + 7.
        Round
        Replace a number with the nearer landmark at a chosen place. 47,382 to the nearest hundred is 47,400.
        Compare · Greater than > · Less than <
        Judge which number is bigger by walking left-to-right until digits differ.
        Regroup · Trade
        Ten of one place become one of the next place up (or one becomes ten of the next place down). What “carrying” and “borrowing” really are.
        Free lessons, assessments & worksheets at WinElements.com  ·  Unlimited online practice at Sleedu.com