0 1 0.1 randRange(1, 9) TENTHS * MARK_INCREMENT SOLUTION.toFixed(1)

Move the \color{orange}{\text{orange dot}} to \color{orange}{SOLN_TXT} on the number line.

init({ range: [ [LOWER_BOUND - 0.3, UPPER_BOUND + 0.4], [-1, 1] ], scale: [350, 40] }); style({arrows: ">"}); line( [ 0, 0 ], [ UPPER_BOUND + 0.06, 0 ] ); style({arrows: "->"}); line( [ 0, 0 ], [ LOWER_BOUND - 0.06, 0 ] ); style({arrows: ""}); for ( var x = LOWER_BOUND; x <= UPPER_BOUND; x += MARK_INCREMENT ) { line( [ x, -0.2 ], [ x, 0.2 ] ); } style({ stroke: BLUE, strokeWidth: 3.5 }); line( [ LOWER_BOUND, -0.2], [LOWER_BOUND, 0.2]); label( [ LOWER_BOUND, -0.53 ], LOWER_BOUND, "center", { color: BLUE }); line( [ UPPER_BOUND, -0.2], [UPPER_BOUND, 0.2]); label( [ UPPER_BOUND, -0.53 ], UPPER_BOUND, "center", { color: BLUE }); addMouseLayer(); graph.movablePoint = addMovablePoint({ constraints: { constrainY: true }, snapX: 0.025 }); graph.movablePoint.onMove = function( x, y ) { return [ min( max( LOWER_BOUND, x ), UPPER_BOUND ), y ]; };
Move the orange dot to select your answer.
graph.movablePoint.coord[0]
if ( guess === 0 ) { return ""; } return abs( SOLUTION - guess ) < 0.001;
graph.movablePoint.setCoord( [ guess, 0 ] );

Above we've drawn the number line from 0 to 1, divided into 10 equal pieces.

The line is divided into 10 pieces, which means:

\color{green}{\text{piece of line}} = \color{red}{MARK_INCREMENT}

\color{orange}{SOLN_TXT} = \color{red}{MARK_INCREMENT} * \color{blue}{TENTHS}

Therefore, moving the \color{orange}{\text{orange dot}} \color{blue}{TENTHS} placeplural(TENTHS) will put it at the position \color{orange}{SOLN_TXT}.

var MI = MARK_INCREMENT; for ( var x = LOWER_BOUND + MI; x < UPPER_BOUND - MI/2; x += MI ) { label( [ LOWER_BOUND + x, -0.53 ], x.toFixed(1) , "center"); }
style({ stroke: "#6495ED", fill: "#6495ED", strokeWidth: 3.5, arrows: "->" }); line( [ 0, 0 ], [ SOLUTION, 0 ] ); graph.movablePoint.visibleShape.toFront(); label( [ TENTHS, -0.53 ], SOLN_TXT, "center", { color: "orange" }); graph.movablePoint.moveTo( SOLUTION, 0 );

The orange number shows where \color{orange}{SOLN_TXT} is on the number line.