LWC: How to add integer value into an array in JS controller which is bound to the data property of lightning datatable

Let's consider the below scenario:

I have a scenario to bind integer value which is calculated from apex function. I have to display integer value in lightning datatable column.

Please find the code below: 

@AuraEnabled(cacheable=true)  
public static Double getTestValue(String recordId){ 
        
        if(recordId == null){
            return null; 
        }
        
        Decimal productAnnualVolume;
        Integer accountCount; 
        Double quantityValue;
        
        OpportunityLineItem oppLineItemRecord = [SELECT Id, Name, Quantity FROM OpportunityLineItem WHERE Id = :recordId];
        productAnnualVolume = oppLineItemRecord.Quantity; 
        
        List<customObject__c> customObjectList = fetchCustomObjectProducts(recordId);
        accountCount = customObjectList.size(); 
        
        quantityValue = productAnnualVolume/accountCount; 
                
        if(quantityValue!=null){
            return quantityValue; 
        }else{
            return null; 
        }
        
    }

JS Controller:

quantityValue; 
accountsData = [];

    @wire(getTestValue,  {recordId: '$recordId'}) 
    getTestValue({error, data}) {
        if(data) {
            this.quantityValue= data;
            this.error = undefined;
            console.log('quantityValue--------->' + this.quantityValue);
        }
        else if(error){
            this.error = error;
            this.quantityValue= undefined;
        }
    }
 

testColumns = [
    {
        label: 'Account Name',
        fieldName: 'AccountName',
        type: 'url',
        typeAttributes: {label: { fieldName: 'Name' }, target: '_blank'}
    },
    { label: 'Quantity', type: 'text', editable: true}
];


@wire(getAccounts,  {recordId: '$recordId'}) 
accountList({error, data}) {
    if(data) {

        let tempAccList = []; 
        
        data.forEach((record) => {
            let tempAccRec = Object.assign({}, record);  
            tempAccRec.AccountName = '/' + tempAccRec.Id;
            tempAccList.push(tempAccRec);
            
        });

        this.accountsData = tempAccList;
        this.error = undefined;
       

    }
    else if(error){
        this.error = error;
        this.accountsData = undefined;
    }
}

HTML:

<template>
    <div>
        <lightning-card title="">
          <div class="slds-p-around_xx-small">
              <lightning-datatable
                  key-field="Id"
                  data={accountsData}
                  onrowselection={handleRowSelection}
                  onsave={handleSave}
                  draft-values={saveDraftValues}
                  columns={testColumns}>
              </lightning-datatable>
          </div>
        </lightning-card>
      </div>
  
</template>

Question: I would need to show 'this.quantityValue' value in the lightning datatable column - 'Quantity'. How could I add 'this.quantityValue' into the 'accountsData' array in JS so that I could be able to display quantity in the lightning datatable. Any kind of help is appreciated. Thank you