I need to generate random 11 digit number which start with 46

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i need to generate random 11 digit number which start with 46

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import java.text.NumberFormatNumberFormat nfNum = NumberFormat.getNumberInstance()Random rand =new Random()for (int i = 0; i < 10; i++) {    int num = rand.nextInt(999999999)    long v = num + 46000000000L    println "v=${nfNum.format(v)}"}

v=46,662,494,557v=46,128,564,160v=46,049,456,673v=46,429,162,366v=46,810,103,861v=46,143,550,931v=46,619,768,618v=46,781,124,745v=46,154,084,133v=46,405,994,498
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i am getting below issue when running above code.
Test Cases/CreditCheck FAILED because (of) Variable ‘format’ is not defined for test case.